Wow, I came here to post the exact same question.
I was planning on occasionally using my iPhone to connect to my work's Exchange servers so that it could replace my very infrequently used work phone. Sadly, it appears according to the leaked AT&T memo, if you plan on using the Exchange features you're required to pay the $45/month data fee. That's just simply not happening for me.
There seems to be quite a few unanswered questions, and it concerns me. I've got until the end of the day to make a decision--I found a guy selling an unused 8GB iPhone on Craigslist for $300. I'm seriously considering just getting this, and playing the wait and see game for the next few months. The phone likely will not lose value--heck, with the way thinks are looking for those interested in unlocking, it might actually increase in value.