No. I've only had my iPhone 4 since February (Verizon launch). Sure, the new one is faster and has a better camera, but I've been satisfied with my phone, so I'll stick with it. I'll wait and see what Apple comes out with next fall, when I'll be eligible for an upgrade.
I don't want to get into the trap of always feeling I MUST have the newest and best. The iPhone 4 is pretty much the only time I've gotten a brand-new Apple product as soon as it came out. We hang onto our computers for years, too. I've got a 7-year-old iBook G4 that I'm just now ready to replace with a used MacBook Pro.
Wendi