So here's is the undocumented keyboard shortcut for triggering Front Row: Command-Escape. Voila! You're using Front Row!
[robg adds: I asked a friend with an iSight iMac to check for me, and he couldn't find that this was documented anywhere. I also searched the Knowledge Base at Apple and came up empty, so here it is. If this does turn out to be documented shortcut, please let me know where you found it...]

