Just for closure on this issue - I figured out why the AWT plugin wasn't working on Ubuntu 9.10. It seems that AWT (and I guess ultimately X?) was unable to gather any mouse/keyboard events for my canvas as long as the canvas's OpenGL context was active - so a minor adjustment to my code and problem solved.
The interesting thing was that I tested this little test app on Windows XP, Windows Vista, Windows 7, Fedora 12, OpenSUSE 11.1, and Ubuntu 9.10 - only Ubuntu 9.10 exhibited this problem.
Anyway, another question: I noticed that the mouse thumb wheel doesn't appear to work for the AWT plugin. No way to get AWT events for the wheel? Maybe I'm just running an old version - but I think my version is the latest.
Anyway, thanks again for the info. JInput is a terrific tool.