Everything I currently have open spells it "Quit". And some of them (Konqueror) don't even manage to have a File menu to put it on. (Ditto on Macs, where it's been Command-Q-for-Quit since forever.) The only place(s) where it's still called "exit" to the best of my knowledge is in command line interfaces (and even there, gdb for one knows "quit" but not "exit") and possibly some bits of GUI API.

Hmm. Well, my small and unscientific sample included Evolution and VMware on Linux, and MS Word on Windows, and they all say "Exit". GNOME and KDE do seem to have pretty much standardised on "Quit" in all their minor applications like games, now I look at it; but my copy of AbiWord on this machine says "Exit" too. So my sample might have been a bit one-sided, but it looks to me as if yours was too.

"exit" still makes some sense in command-line interfaces, of course, since there often is a suspended shell to which the easiest way to return is to terminate the foreground CLI application.

*checks*

opera says exit, sylpheed says exit. I don't appear to have anything else clicky open, except xdvi which doesn't have a special button for closing it.

My copy of Evolution says 'Quit'. As do Firefox, X-Chat and Gaim. Gnumeric and Abiword both offer 'close' and 'quit', with apparently the same result unless I'm missing something.

*starts exploring menus*

OpenOffice Writer has 'exit'. That's about the only one I can find on this machine (Debian Linux, predominantly running GNOME applications).