seconded - this issue appears with quite a few different titles so far...
easiest (short-term) fix is to create turn off the screen you aren't using, and then restore it after you're done playing.
actually, I just discovered it's not a showstopper (as with other games): it's simply choosing the wrong default resolution at first startup. Once I adjust the resolution from 2960x1050 to 1680x1050, it disables my second monitor (black) and procedes on my main monitor, which is good! Only thing, it somehow confuses steam about the screen order upon quiting the game: my friends list which is always on my left (secondary monitor) turns up on the same position but on my right monitor, same with the main steam window which is normally on my primary monitor
Most likely a trickle-down issue from Shank (1). There is a related bug report filed at https://bugzilla.icculus.org/show_bug.cgi?id=5358.
Was this issue directly brought to the attention of Alternative Games?
personally, i can't test anymore since I don't have a dual monitor setup anymore (2nd monitor broke down :S)
afair, i did not inform Alternative Games
Nothing extracted yet.
using fullscreen mode in Shank 2, it shows the single screen centered over both monitors instead of on the primary monitor.
using nvidia twinview