Even though I'm 80, I still haven't switched out all of my gear. Perhaps the most surprising thing is that I'm still wearing my T4 helm.
I just haven't had anything better drop for me in Northrend yet. I know there are BoE upgrades and quest upgrades from the Icecrown quests, but I haven't gotten to them yet. There's also a slew of gear to be had in heroics.
Aside from my helm, I'm still wearing my legs and a spell hit ring from TBC, but those were badge items from the Isle of Quel'danas so it's not surprising those are still good since they'd arrived as part of the Sunwell patch.
Now that I'm finally 80, I'm really looking forward to starting heroics. I also have almost all of Sholazar Basin to finish as well as Icecrown and the Storm Peaks left to quest in. Some of my best in slot gear for Naxx are BoE crafting epics so I'm gonna need the cash to either buy the mats or the items themselves.
And for those in the US, have a Happy Thanksgiving! I'm going to be heading out soon myself. I'm already hungry... hehe...