All activating virtualenv does is set up a bunch of environment settings (PATH, PYTHONPATH, etc). They provide activators for bash and csh; it wouldn't be hard

All activating virtualenv does is set up a bunch of environment settings (PATH, PYTHONPATH, etc). They provide activators for bash and csh; it wouldn't be hard to set up the environment for M-x eshell, even if it was a little more manual process.