RadioShack has tweeted that the T-Mobile Sidekick 4G handset will hit its retailer location on April 20th. Sidekick 4G runs with Froyo, 1GHz A8 Hummingbird Processor, 3 MP primary camera, 3.5-inch display and, Samsung Media Hub, plus Qik video calling and DriveSmart and more. Check out the tweet by Shack and more details of the TMo's Sidekick 4G handset here.