One of the new Windows hotkey combinations is :
Windows + Print Screen
If you press it, a screen shot is taken after a tiny dimming of the screen [like a shutter release], and stored in your Pictures library. The file name starts as Screenshot.png, then Screenshot (2).png, Screenshot (3).png, and so on.
It’s quite nifty but it doesn’t seem to do multi-monitors very well. It always takes a picture of the primary monitor, even when your focus is on the secondary monitor. Still that might be an issue that is already being worked on ready for the final release of Windows 8.