I installed python 3.3.1 on ubuntu lucid and successfully created a virtualenv as below
virtualenv envpy331 --python=/usr/local/bin/python3.3
This post on the bitbucket issue tracker of virtualenvwrapper may be of interest. It is mentioned there that most of virtualenvwrapper's functions work with the venv virtual environments in Python 3.3.
You can make virtualenvwrapper use a custom Python binary instead of the one virtualenvwrapper is run with. To do that you need to use VIRTUALENV_PYTHON variable which is utilized by virtualenv:
$ export VIRTUALENV_PYTHON=/usr/bin/python3
$ mkvirtualenv -a myproject myenv
Running virtualenv with interpreter /usr/bin/python3
New python executable in myenv/bin/python3
Also creating executable in myenv/bin/python
(myenv)$ python
Python 3.2.3 (default, Oct 19 2012, 19:53:16)
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
virtualenvwrapper now lets you specify the python executable without the path.
So (on OSX at least)mkvirtualenv --python=python3 nameOfEnvironment
will suffice.