Hit the PrintScreen key in the Ubuntuized GNOME 2.10.0. Up comes a save dialog
with a preview of the screenshot. There are also two fields, "Name" and "Save in
Folder." Try typing a name *and* path in the Name field (e.g.,
"~/Screenshot.png"). Click OK. Then look for that screenshot file. It will have
disappeared -- the save will have failed silently.
Other GNOME2 apps don't behave this way. Evolution doesn't, for instance, and
Firefox (which I believe is using GNOME2, but I'm not sure) doesn't either. I'm
surprised that the save dialog isn't more standardized, such that it would be
impossible to use non-standard behavior like the Take Screenshot applet does.