I experienced the same problem on busy weekends last year. I think it is system overload. If I have a problem now, I just switch back to edge and it is faster than 3G.
We are fortunate in that our 3G is normally good. FWB has terrible 3G.
Most of my friends here have Iphones. Every one of them is having service issues that they said they never had before until 2 days ago. Spring breakers? Speaking of which, holy traffic and accidents to and from Destin this week!