OK, one of my questions has been answered and it isn't what I was hoping for. According to the AT&T press release, the new iPhone 3G data plan will actually increase US$10/month to US$30/month. In addition you will need a voice plan starting at US$39.99/month so the total monthly fee to use an iPhone 3G will increase US$10/month or US$240 over the life of the new 2-year contract.
Business users monthly data access will be US$45/month in addition to a qualifying voice plan so you may want to keep your iPhone 3G devices designated as consumer devices.
I knew there had to be a catch with these low iPhone prices and maybe this is why Steve Jobs never mentioned anything about AT&T or data rates in the keynote and just put the subsidized price of the iPhone 3G out there. The new pricing scheme also means that AT&T will no longer be kicking back any monthly fees to Apple. Hmm, this makes you wonder how much premium Apple was making on the first generation devices, huh?
There is nothing in the press release about current generation iPhone plans, but hopefully they stay the same since they are limited to EDGE data with the current generation iPhone.
Thanks to Kevin Tofel for the link to this press release.