Acti just confirmed a March 30 launch for Modern Warfare 2's first DLC pack, a date teased last night.
The Stimulus Pack will, as promised, release on Live first.
Additionally, Silver Live members will be able to try out MW2 online play in a "Multiplayer Unlock event" running from March 12-15.
There are no details on the included maps themselves so far, although it seems likely supposedly leaked shots recently were real.
This is the first of two DLC packs for MW2 from Infinity Ward this year.
There's a press release here.