There are a lot more fully informed opinions on Apple iPhone SDK announcement, but here are a few of my thoughts as to how it relates to my own personal world...
Apple struck a good compromise on control versus freedom. I think most people are happy with the benefits and willing to accept the limitations.
I have never tried the Apple Xcode development platform... I might have to spring for a mac mini =)
No 3G or GPS announcement. I think 3G is eminent, but I'm skeptical on whether they will ever integrate GPS.
With the added enterprise features, RIM has every reason to quake in their boots. With a simple firmware update, Apple has swallowed RIM's business turf. The only thing that is left is the hardware keyboard versus the touch screen keyboard.
I think I'm going to at least wait until June to see some of the stuff the SDK can do, and hopefully Apple will release a hardware refresh with 3G in June as well. In any case, I don't think it makes sense at this point to jump on gen1 hardware.