According to these sources, RIM held a large number of events for retail representatives across the USA, including with T-Mobile ones. It's reported that it has become clear during these events that both the BlackBerry PlayBook and the BlackBerry Storm 3 are coming to Big Magenta customers at some point in the future.
Moreover, it's said that one of these devices - our bet is the BlackBerry PlayBook, since the BlackBerry Storm 3's expected release date is in Q3 of 2011 - is scheduled to join the T-Mobile ranks very soon.
Until we have more info, we will treat this report as a speculation, but surely it sounds exciting for T-Mo customers. The pic below (showing the BB PlayBook) is said to be taken during a T-Mobile - RIM meeting.
source: T-Mo News