ICS had a prototype / dummy model M3 grease Gun on their wall really high upat the 2011 Shot Show according to AirsoftOhio members. It's apparently in their 2011 catalogue and according to their rep at the Shot Show it's going to be ready for summer 2011.
When it actually hits retailers is anyone's guess.
I think the rep wasn't so sure about what mag it'll take.
FF to 3:45:
YouTube - ICS at 2011 Shot Show