Suddenly I have to manually trigger compilation of all classes I change. Nothing is automatically picked up. This happens for all versions I have installed; basically almost every version in the 8.x series, 9M1, and the Maia EAP.
This is on OS X, running with SDK 1.6.0_15.
I've tried deleting all traces of IDEA (application, preferences, and cache), re-installing with specific set of plugins and re-installing with just default set of plugins. Since this happens across versions it might seem like it's caused by something else than idea itself, but I see no errors or warnings during startup.