Mythbuntu is a distribution based on Ubuntu, that has replaced the usual office applications with MythTV, to transform your computer into the ultimate Media Center. If it was already quite usual to start seeing computers focused on living rooms, with the appearance of the Mythbuntu system it's going to be even more common, because it allows us to tune into the TV, record whatever we are watching, or connect remotely to a server. The functions a real Media Center should be able to implement.
Mythubuntu is based on Ubuntu, but as we have stated before, without the normal office applications that wouldn't have any use in a Media Center, even though they can be installed if you want from the Control Center. It also includes codecs, drivers, the Xfce graphical interface and of course MythTV, plus specific programs to manage the whole system from Mythbuntu.