I tried the hard reset, *228 reset, Airplane mode (on/off cycling), and just about everything else that was suggested. After reading up somewhere that it may be an issue with advanced task-killer, I looked around to see if there was anything in particular that I'd shut off or altered.
Problem solved. My issue had to do with the way I'd changed my settings to prevent inadvertent 3G charges.
1) Settings
2) Data Manager
3) Data Delivery
Under Data Delivery, make sure the option of "Data enabled" is checked. Again, I know it won't be a fix for everyone, but it's worth a look if anyone else tweaked the phone there or worth some consideration if you have an external program to control 3G usage (specifically those that block it after reaching a certain point to prevent overcharges)
Hope it helps.