The jobs are divided a bit differently but the combo of gem/rvm/bundler is matched quite nicely by pip and virtualenv (with virtualenvwrapper adding some nice conveniences)

This article covers some of the equivalent jobs using Ruby and Python:

http://gillesfabio.com/blog/2011/03/01/rvm-for-pythonistas-v...

The article misses covering the freeze command in pip which is great for generating requirements.txt files:

pip freeze > requirements.txt

Covered in detail here: http://www.pip-installer.org/en/latest/requirements.html