I think it only makes logical sense for Apple as a company to not release a new phone so soon. With Verizon getting the phone in like February and the unlocked phones coming out THIS month...it makes no sense for Apple to release a new device until they have sold enough iPhone 4s across the board (AT&T, Verizon, and Unlocked). I think the best bet for any kind of iPhone being released this year would be September, if that. Personally, I'm thoroughly happy with my iPhone 4. There are some things I wish that I would have (a bigger screen, 8MP camera, etc.), but I should be happy enough to have a phone that JUST WORKS...with everything. iOS 5 really makes the phone experience 10x better in my opinion and I think all iPhone 4 owners will feel like they have a new device after upgrading (I know I did).
-Adam