Samsung has been working to push Ice Cream Sandwich to the entire Galaxy Tab series as of late. We've already seen it hit the 7.0 Plus Wi-Fi, 7.7, and 10.1. As usual, owners of carrier-connected tablets have to wait a bit longer, as the update has more hoops to jump through before it can get the final approval and make its way to said devices.
Looks like T-Mobile is among one of the first carriers to offer the update for its variant of the Tab 7.0 Plus, and it's scheduled to become available tomorrow. However, this one isn't coming over-the-air (OTA); you'll have to turn to Samsung's proprietary Kies software to grab the download.