Yet, there is one feature I missed dearly, so I set out to make it: JHBuild did all of it's building in the same directory where the source code was check out, and this interfered with my work habbits. First of all, my CVS checkout of Gnome apps is on a separate partition that doesn't have too much room to spare. Also, I like to keep my primary CVS checkout tree clean, because I do commits all over the place, and if build system changes something, or I hack something to make it work, I may later commit accidentally something I didn't mean to.
So, better separate it out. I've attached a patch to do that along with a RFE (Request For Enhancement you unenlightened folks) in Bugzilla as bug #131296.
Go ahead and post your comments and suggestions either here or in Bugzilla (you'll need to register an account for Bugzilla).