rip isn't just a mix of pip and virtualenv though, it's also got bits of functionality from virtualenvwrapper (manages multiple envs) and buildout (plugins) mixed in there.
There is no way to work with gems in a development format? e.g. straight from version control?
I like Buildout's approach of doing script generation better though, since it allows for multiple working sets of packages within the same environment. And you can manage stuff besides just language-specific packages, such as database installs, config files, etc, etc. Plus you can manage libraries from more than just one language - perfect for those franken-Python-Perl-Ruby projects.
Looks like a big improvement over the rails/gem_dependencies sillyness of embedding a package management tool into a web framework though!