Has been since at least Windows 3.1 (and DOS before that, for text content). And, in Windows, Alt-PrintScn captures the window in focus.
The capture programs allow you to specify a custom area of the screen for capture, view it inside a lightweight viewer and maybe do some minor editing. XP has a clipboard viewer, but it's pretty much deprecated (run->clipbrd). Windows 7 drops the clipboard viewer entirely and adds the snipping tool, which has similar functionality (not quite as good) as the tool Jim recommended.
They don't do anything you can't do with the print screen key and an image editing program.
Best regards, Spehro Pefhany