This is intentional. Debian Sid does not provide xlibmesa-glu-dev either, and we realigned (mostly) with Debian Sid's packaging at the beginning of the Edgy dev cycle.
$ apt-cache rdepends xlibmesa-glu-dev shows that no packages depend on xlibmesa-glu-dev directly, and checking $ apt-cache show freeglut3-dev |grep ^Depends demonstrates that xlibmesa-glu-dev | libglu-dev is required. libglu1 -mesa-dev provides the latter alternate, and indeed freeglut3-dev installs just fine on this current Edgy machine. ** Changed in: xorg (Ubuntu) Status: Unconfirmed => Rejected -- xlibmesa-glu-dev is not available in Edgy https://launchpad.net/bugs/61267 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs