Why are some apps greyed out when Command+Tab'ing through programs?
I recently read that the command+tab switcher no longer strictly shows a list of running apps, but is instead the combined set of running apps AND recent apps. The Mac OS now (much like iOS) kills off apps that have no open documents or otherwise don't need to be running (in its infinite wisdom). My GUESS is that the greyed out apps in the switcher are recent-but-not-running apps.

Annnd ... I just read that you're running 10.6.8. So, yeah, never mind that answer.