I built an ebuild for roundup this evening using ebuilder; very cool! The generated ebuild has the line: python setup.py --root= --prefix=/usr install || die, which isn't quite right. The "install" needs to be before the --root and --prefix options, and the root option should read --root=${D}. That said, the fact that ebuilder even knew to use distutils is truly amazing!
I suspect Zach is in a much better position to come up with a fix, as this is his baby. Reassign the bug back to me when you've uploaded a fixed version on disinformation.ca
ebuilder-0.4-r1 should fix this