Word is Engadget Mobile received an email telling them T-Mobile is planning some kind of special event on April 21st.

Unfortunately the email didn’t include any details as to what would be going down at this event other than it is a “private launch event” in NYC.

So just what T-Mobile will be launching is anyone guess, could it be Cupcake? Maybe an official view of the Sidekick that’s just been going through the FCC or maybe T-Mobile is going to officially unveil the HTC Magic over in the US. Guess we will find out on the 21st.