Last night I finally managed to build with jhbuild on the Gentoo machine (details here). This afternoon I'm working on getting the same to work on an Ubuntu VMWare installation. This will be a full Ubuntu install with the sugar-jhbuild/jhbuild configuration and build complete. At the moment sugar's sound is broken, so it won't have that, but we'll update the image when csound is available (and when there is any point that can be considered a usable stable target.
We'll probably put those up either on the google code group or somewhere linked from the OLPC wiki page.