Yeah, and not just that, but those in both groups who need a bit of a pep talk. I'm tentatively working up the courage to dive in and put my bear suit back on after spending all of Wrath healing either as a druid or a priest, and I've been hesitant to actually click the queue button, knowing from experience what a pain in the butt undergeared tanks can be for healers. But that last bit about keeping with it is really important.

I'm probably going to be rusty. I'm probably going to be a bit undergeared. I'm probably going to cause some stress for some people my first few times out. But in the long run, I know I'm a good tank. If I can coordinate and successfully lead the first pull in Gruul's Lair, I'm pretty sure I can handle anything I might see in a Cataclysm 5-man, once I get my tanking legs back.

@Smoke - Just go slow. I've healed many a tank who just hit the ilvl requirement, and it's not bad as long as they don't try to go too fast. The fact that you didn't tank in Wrath probably works in your favour: you have to get back on the bicycle, but you don't have to re-learn, for instance, that you have to use hand breaks instead of pedalling backwards (how some bikes stop).

There is one thing I would also add to this article:
"if you're going to tank in WoW, you have to choose the right class."
I would also recommend to start tanking as soon as lvl 15. First dungeons can be tanked even if you are not specced as a tank, and dual talent comes fast and cheap. This way, when you reach lvl85, you will already know the basics of tanking (LoS,, etc), and queuing to dungeons as a low level tank gives you lots of XP, fast leveling, great loot and no wait time.

Another tips to be newbie tanks. Enchant your gear, no matter your level.
The general attitude to enchanting seems to be "End Game Only", but enchanting as much of your gear as you can afford to can be the difference between a wipe and a close shave.
This also helps in situations described above, when you as a tank have just hit the barrier of entry for a LFD. Enchanted gear, can stretch a lot further than hoping for a drop in dungeon where you're taking a lot of hurting.

Another sneaky tip while leveling up, before levels 40, 60, 70 do some BGs.
The Honour armour is pretty decent and you'll learn a lot about surviving and using your cooldowns in BGs.
Take this armour set for Pallys for instance: http://www.wowhead.com/itemset=698
3 pieces reduces the cooldown on your hammer of justice by 10 seconds. Thats pretty dam decent perk to get you through outlands.

@Ryan - When I'm in the LFG whilst leveling, I heal on my shadow priest, heal on my elemental shaman, the list goes on. You DO need a tanking spec to tank lower level dungeons, but enchanting all your gear is extreme overkill, unless you've taken enchanting as your profession.
Remember this is wow rookie, the people learning from this won't have an 85, and they certainly won't have the gold to spend on overpriced enchantments.

Is there a similar one for newbie healers? I need that one :)