PEP-405 is recommendation to include some virtualenv-like like functionality into the python stdlib. I suppose this idea might actually fly if python were driven from a single PYTHON_HOME or PYTHON_PATH env variable and for the most part it seems that PEP-405 suggests that potential.It should be noted that this PEP was also endorsed by Ian Bikling the inventor of the proper virtualenv. –PEP-405There is some discussion about backward compatibility but it is sort of vague and very mystical in a hand waving sort of way. One reason it might actually work well is that one application like the current virtualenv toolkit does not have to carry around all of the version info needed to work in each python version.But let’s be clear. PEP-405 is not virtualenv. It is virtualenv-like. It is also approved for deployment in version python 3.3 and I do not see anything about back porting.Virtualenv is a killer feature. If they miss the mark and abandon all that came before I hope that someone picks up the slack.