Wrath of the Lich King has created a new standard for sheer volume of content available to players as soon as they hit max level. And with content, comes gear! Reputation grinds such as the Argent Crusade and the Kirin Tor can be completed in only a few days, even if you schedule time to deal with things like 'real life'. Crafted gear is mostly bind on equip now, making it much more accessible. Several heroics, such as Utgarde Keep, Violet Hold, and Nexus, are easy enough that a DPS can usually slip into them shortly after hitting 80 without slowing their group down. Even the 10- and 25-man versions of Obsidian Sanctum and Vault of Archavon, are frequently cleared by pick-up-groups.
Head slot items for warlocks are pretty much limited to three right now. My current favorite is The Argent Skullcap, attained through a rather simple quest-chain in Icecrown. The high amount of hit rating makes getting that all-important 446 much simpler, and it's far easier and cheaper to get than either of the other two pre-Naxx headpieces. Though if you're a tailor The Hat of Wintry Doom may serve as a skill-up for you. And if the Forgotten Shadow Hood happens to drop in Heroic Culling of Stratholme, it's also a good choice. However, that 446 hit rating has to come from somewhere, and I've rarely seen any piece of gear with as much as The Argent Skullcap has.