April 20th is looking to be quite the day for T-Mobile fans as T-Mobile has announced both the availability of the G2X this morning along with…drum roll please…the Sidekick 4G. Dropping April 20th in stores and online the Sidekick 4G will cost $99.99 after a $50 mail in rebate. Turns out that Radio Shack tweet was on the money after all. Sidekick fans better start your calendar countdowns!