PC Borderlands players have had to wait up until now, but the first DLC is now available. The Zombie Island of Dr. Ned can be purchased at the link below for those who have a retail copy, and via Steam or Direct2Drive those who downloaded the game over the interwebz.
Nick's impressions of the DLC were quite favorable, and he describes it more as an expansion pack than your average DLC. Seems like The Zombie Island of Dr. Ned is certainly worth the $9.99 price tag!