While T-Mobile's staying coy about the Sidekick 4G's availability, RadioShack went ahead and gave us the final piece of the puzzle: according to one of its latest tweets, said Android phone is heading to the Shack on April 20th. Oh yes, this just so happens to be the rumored date for the G-Slate and G2X as well. Coincidence? Only time will tell, and let's hope that this doesn't end up being an April Fool's joke -- well, at least the Shack would have something to blame if it actually misheard the information over the phone.