I noticed the same problem starting Saturday. Data, safari, email, and weather and stock widgets are hit and miss, all call features work fine. I always have good signal and the edge icon is always present but it seems to cycle in about 15 minute intervals. Other coworkers have had voicemail problems. It's nice having a $500 paper weight isn't it.
At&t checked towers in my area and said all is fine but I think they have problems they haven't discovered yet. They also de-activated and re-activated my data service without success. I have done everything possible to the phone except a complete system restore. I've powered off, restarted, toggled airplane mode, reset network connection and all failed. AT&T admits no guilt, haven't called Apple, but it doesn't sound like it's the phone.
I am in Cabot, AR.