Symptoms include not being able to start up eclipse anymore. It complained about not finding Java on my path, where things reported just fine in a terminal. Turns out there are two paths in Mac OS X: one for the terminal and one for GUI apps. The first one is your classis unix $PATH, the second is found in ~/.MacOSX/environment.plist. Live and learn, I guess.
After this interruption, back to my regular programming (pun intended).