Out of all the toys that shamans will be getting in the expansion, one ability jumps out as particularly useful for PvP: Spiritwalker's Grace. Imagine elemental and restoration shaman retaining their mobility while casting spells with a casting time. This will improve their desirability in small PvP environments such as arenas, but at the same time provide much needed mobility to a class that is sorely lacking in that department. On the other hand, shamans got hit hard by the changes to dispel mechanics because of the loss of their fire-and-forget Cleansing Totem and their loss of poison and disease dispels. The tradeoff, of course, is that the restoration tree gets a talent to remove magic. You win some, you lose some.
And then you win some more. Spirit Link, an ability that didn't make it through Wrath's beta phase, is attempting to make a comeback. We'll also see elemental shamans get the old Warcraft 3 ability Earthquake, a targeted, persistent AoE spell, which interestingly enough bypasses a rogue's smoke bomb. They will also get Unleash Weapon, which sadly sounds like the shaman version of paladin judgements, but at least gives shamans of all specs some instant-cast, offensive utility aside from shocks. Overall, nothing truly remarkable for shamans in PvP, not even the respective masteries of the different specs.
As mentioned, warlocks are going to be very exciting in the new environment, thanks to the soul shard mechanic overhaul. One interesting ability that would need more clarification to generate excitement and proper analysis would be Demon Soul, which fuses the warlock with her chosen demon to gain specific effects. It would be cool to find out what kind of effects will be available and which will be geared towards PvP or PvE utility. It's pretty clear Blizzard has PvP in its sights because of a few changes done to the class. For example, the new Whiplash ability of the succubus knocks back opponents, which should extend its PvP survivability somewhat.
Furthermore, warlocks in Metamorphosis or demon form will be immune to demonic fear such as Turn Evil, which means that the paladin's Glyph of Turn Evil will probably lose its PvP appeal in the coming environment. A demonology warlock's abilities while Metamorphosed will be altered to reflect her own abilities, which is a welcome change considering that the abilities of a Metamorphosed demon were jarringly different from that of a caster class. Shadow Cleave? Demon Charge? Challenging Howl? It was as though Blizzard suddenly wanted warlocks to melee tank. It didn't make sense at all and something we'd pointed out, oh, since the beginning of Wrath. Warlocks should look forward announcement of the new abilities while Metamorphosed, as there's a good chance of gaining some PvP utility or survivability there.
Warlocks also get some sort of killing blow ability with the Shadowburn talent, which deals more damage to opponents below 25% health, although it probably won't replenish a soul shard in the same manner. The masteries also further define the distinctive playstyles of all three specs: affliction will be all about shadow magic DoTs, demonology will be all about pets and destruction will be all about direct damage fire spells. Blizzard did a great job making each spec distinct in Wrath, and they're following through even better in Cataclysm.
Provided Blizzard can fix pathing issues, targeting and possible exploits throughout the beta, Heroic Leap will be making a comeback in Cataclysm. Purely because of its positional nature, we're putting this one as a PvP ability. Thunder Clap and stun effect in one jumping ability? Yes, please. There's also a small change to Whirlwind which puts a damper on it being used against single targets (hint: it wasn't meant to), but the change to it being usable on an unlimited number of targets is the funky part. Think defending a bunker. Think the chaos of taking down the enemy general. The more enemies clumped together in one place, the better. Considering that Cataclysm PvP is shifting towards large scale environments, this might be even more fun than its original, hard-hitting version.
One important note tucked away in the warrior class changes is Blizzard's statement about healing in Cataclysm. As mentioned, there'll be more health and less healing. To keep up with these changes, the environment-defining Mortal Strike is being
Furthermore, Blizzard is considering changing all Mortal Strike effects to apply a physical -- or undispellable -- debuff called Mortal Wounds. This puts all these effects on even footing, as opposed to, say, Wound Poison or Permafrost being dispellable. The lowered value also standardizes the effect across all classes. These aren't specifically warrior changes, but since Blizzard tucked it in the discussion, we might as well mention it here.
Warriors also get a few other things that we're likely to see in PvP encounters, such as the new arms talent Disarming Nature. The fear effect is such an amazing crowd control ability that warriors will have reason to use Disarm even against casters. Will damage break the effect? We don't know for sure, but it's an awesome talent, anyway.
Other changes of note
Another thing that can be observed in the spate of class changes is the Frostfire Bolt effect, or giving spells two dimensions of damage. It appears as though Blizzard is making magic schools matter more when it comes to damage, and gave certain classes spells that work off two or more magical schools. Warlocks get Fel Flame, which deals shadow and fire damage, while survival hunters have a mastery that allows some abilities to deal elemental damage. Balance druids are encouraged to mix it up and deal arcane as well as nature damage. Frost mages have a mastery that encourages the use of spells outside Frostbolt. There are other talents and masteries that push the different magical schools to the fore, such as increased nature damage for enhancement shamans and increased holy damage for retribution paladins.
Does it mean anything? We can't tell for sure. It could be that Blizzard is merely delineating spell sources and preparing players for elemental bosses who normally have high resistances against particular magical schools. It could also mean that Blizzard is placing increased importance on the type of magic used for a spell (or even physical damage -- as the Cobra Shot as a Steady Shot alternative shows). This might impact PvP in some way, which should make things incredibly interesting. Of course, the removal of school specific resistance spells such as Fire Ward and Frost Ward seem to indicate otherwise, but it's certainly food for thought.
Suffice it to say, PvP will change dramatically come Cataclysm. The outlined changes don't even begin to cover everything we'll be seeing in the coming months, as Blizzard has explicitly stated that it will be removing all passive, unexciting talents and replacing them with abilities that have concrete, discernible effects. That means talent trees will play a bigger role than ever. All that and we haven't even delved into the Path of the Titans yet. You'd better brace yourselves, because we're in for one hell of a ride.