apt-builder may show some promise.
I stumbled upon pbuilder
http://packages.gentoo.org/search/?sstring=pbuilder
http://www.netfort.gr.jp/~dancer/softwa ... r-doc.html
Which raises the question of cross-compiling, both across distros, across different processors, and across versions of gcc. I remember getting into awful trouble after gcc/glibc upgrades when I forgot to recompile my kernel.
Does anyone have a setup that works particularly well, or know anything that I'm likely to stumble on that might break horribly and/or inexplicably?