Metacity, the default GNOME window manager of the former GNOME 2.x days, will find itself no longer on the Ubuntu install image and will soon be removed from the Ubuntu "main" archive.
From "Farewell Metacity" on the ubuntu-devel list:
The below upload of ubiqutiy adds compiz as the supported window manager during installation via Install Now option. This means if on the CD no other ubiquity supported windows managers are present compiz will be used as the last fallback. In practice this means that metacity will fall off Ubuntu Desktop and Ubuntu Nexus images as of next build with this ubiquity version included. No other images/flavours should be affected.
Metacity will still be in main for a little way, the only thing that holds it back is reverse build dependency of openjdk. I will follow up with openjdk to see if it's possible to drop metacity dependency and move it elsewhere (dep-8 / separate source package etc).