I can still save files by hitting Ctrl-S, but only over the top of the original file. I don't get prompted for a filename to save under, nor do I get a chance to save it into a different directory.This is not a bug. Gimp is intentionally context sensative. You can have multiple images open at once, how does it know which file you mean?
You can highlight "Save As..." with your mouse and hit Ctrl-Shift-S, and so this shortcut becomes bound to this command. Really works!
joerg