Here is my xmonad config required to run xmonad inside gnome session with hacks for youtube, flash full screen video etc.
Just copy paste it to .xmonad/.xmonad.hs and issue a xmonad —recompile command.
To make xmonad as the window manager for gnome, issue the following command,
gconftool-2 -s /desktop/gnome/session/required_components/windowmanager xmonad --type string
Xmonad config: