I must say this is good timing for me. I've just been looking into finally jumping on the Iphone bandwagon, and buying a 16GB 3GS. With the Iphone 4 announcement, it's already dropped from $879 to $799. And the 32GB version is now down to $879.
With that in mind, I think I'll still go ahead with the 3GS. For me, the extra features it has over the 3GS isn't compelling enough for me to spend an extra couple of hundred or so (whatever the price will be) for it.
Higher resolution screen? *shrugs* the 3GS looks good to me.
Video calls? *shrugs* I hate webcams, so it's not something I want on a phone.
Multitasking? *shrugs* I've got a computer for that.
Sexier design? *shrugs* it's a phone.
One more reason to look forward to tax time......