Rhythm in open source

Mark Shuttleworth (what an awesome last name, BTW) thinks that KDE, Gnome and OpenOffice.org would benefit from a common release schedule, preferably six months like Ubuntu. I'm wondering if Eclipse's annual release trains also influenced his opinion and whether these kind of coordinated/rhythmic releases have been done elsewhere in the open source world or are Eclipse and Ubuntu the only ones? I think it would be great for the open source community if the rhythm spread and releases became more predictable.