Steam news has a note saying Monaco: What's Yours Is Mine is currently 60% off as a daily deal. As reported on Rock, Paper, Shotgun, the heist game has also received a huge free content update as well (no room for that amid pages of DOTA 2 patch notes?). The update includes a new mini-campaign and Halloween-themed zombies while adding support for Linux and the Steam workshop. Here's word on this gratis patch:

FREE HALLOWEEN UPDATE!

Monaco Origins
New Mini-Campaign featuring the back stories of the 8 original characters.

Zombie Mode!
Zonaco - Your Flesh is Mine featuring new enemies, new strategies, new gameplay.

Linux
Yes, this means Steam OS!

Now with Steam Workshop!