Starting at 1:30 a.m. PT on Friday, T-Mobile Sidekick users experienced a major service outage that in some cases caused all internet connectivity to be lost intermittently.
Danger, Inc. a Microsoft subsidiary part of the new Premium Mobile Experiences (PMX) team, has been working to restore lost service and solve the problems which caused the outages.
Not all users have been affected in the same way. Some users reportedly could not access their address book, while others may have experienced temporary outages since the problems began.
Source: CNET