Hothead Games say they've listened to their fans, and on October 26 the first Deathspank-game will be released for PC on Steam (with a Mac version to follow on a later date). It will be available for $15, which usually means €15 for us, and there will also be a pack where you get both Deathspank and Shank (called Shank and Spank) for $25.
No word on an exact Mac-date, or if Deathspank: Thongs of Virtue will get the same treatment.