Our good friend Kestrel reminds you that as you're leveling up and getting all this new gear, there are quite a few good tools out there to let you know what's what in terms of what gear is best for you. Lootrank is the one Kestrel mentions most -- you can put in your own stats and check off which ones are most important to you, and it'll recommend and rate your gear from there. We've got our own list of other sites which will help, too -- Kaliban's great class loot lists (at wow-loot.com) have been all updated for Wrath, and of course ShadowPanther has lots of Rogue updates as well (though DruidWiki doesn't appear to be completely updated yet).
MaxDPS.com is a very popular site for seeking and tracking gear upgrades as well, and I remain a fan of the simplicity of Gear Wishlist -- it doesn't get any easier than tossing your info into a form and having the site spit a huge list of gear options at you, based on the rankings from mulitple other sites.
But no matter how you do it, there are plenty of ways to figure out which way to head for your next upgrade. There's a whole continent of new gear out there -- go get some.