The first DLC for Borderlands, the Zombie Island of Dr. Ned, is out today.  For 800 MS Points ($10), you can get your hands on this new content.  It has an estimated 6-10 hours of expanded gameplay, which would make it well worth the money.  Borderlands has been out for about a month now and a full featured DLC is already out.  Cheers to Gearbox for their hard work.