I just came back to iPhone after a brief foray in the Treo 750 WM-6 world and, since the T750 is 3G; I had a chance to observe battery usage and availability of 3G in my area.
In most of my daily travels, I have no 3G availability. Thus the 3G iPhone would not be a big benefit. Yes the "me.com cloud" would be useful but I can always sync my iPhone to my notebook and then sync my iPhone with my desktop when I get home. In all these years, I have never accessed my home iMac from the road. Thus, I never leave it turned on!
Other 3G dependent SDK Apps, while handy, are not a big necessity for me.
So, I'm with you: I'll wait for iPhone 3.0
Bill