There was a widespread (global?) Internet outage on the T-Mobile network Monday morning, March 18th 2012. As of 1PM Chicago time, customers are still being asked by tech support agents to "remove the battery of your phone while we re-force your SIM card back onto the network."
Further details were not available, and the T-Mobile representatives are unaware of any official network status page to describe outages or restoration times, short of suggesting that one "Googles" for information.
Incidentally, simply rebooting the device ultimately worked, and literally removing the battery was not required - as long as the reboot occurred after the system was back online.
The root cause was attributed to a router upgrade that went south, and the outage was allegedly "mostly on the East Coast" although it was also experienced in the Midwest.