Team17 recently revealed the first batch of downloadable content for the Xbox Live edition of Worms in this thread on their official forum. It's pretty much what you'd expect -- voice packs and map sets -- but the surprise is the price tag: free!

PREMIUM DLC
Gamerpics 150 pts (standard MS pricing)
Worms Dashboard Theme 150 pts (standard MS pricing)

DLC
Speech Pack 1 (FREE) - A dozen or so speech banks. **
Space Theme & Audio (FREE) - New background level to play on
Audio Pack (FREE) - Various background audio and Worms theme

Expect additional speech packs, level themes, more audio, gamerpics and dashboard themes from then on. Some of the content will be charged, some will be free.

**Africaan, Angry Scots, Classic, Cyberworms, Danish2, DanisPyrus, DoubleohSeven, Dutch, Dutch2, Finnish, Greek, Hungarian, Irish, Norwegian, Polish, Portuguese, Redneck, Russian, Scouser, Stiff Upper Lip, Swedish & Swedish 2 (Note: It is currently hoped that all speech banks will be supplied FREE).

This announcement came from the 13th but more recent posts on the forum lead me to believe that we should be expecting this update any day now, along with the much-needed first patch to the game.

via XBLArcade.com