Distributing python code with virtualenv?

You can use a tool like PyInstaller for this purpose. Your application will appear as a single executable on all platforms, and include dependencies. The user doesn't even need Python installed!

See as an example my logview package, which has dependencies on PyQt4 and ZeroMQ and includes distributions for Linux, Mac OSX and Windows all created using PyInstaller.

Buildout - http://pypi.python.org/pypi/zc.buildout
As sample look at my clean project: http://hg.jackleo.info/hyde-0.5.3-buildout-enviroment/src its only 2 files that do the magic, more over Makefile is optional but then you'll need bootstrap.py (Make file downloads it, but it runs only on Linux). buildout.cfg is the main file where you write dependency's and configuration how project is laid down.
To get bootstrap.py just download from http://svn.zope.org/repos/main/zc.buildout/trunk/bootstrap/bootstrap.py
Then run python bootstap.py and bin/buildout. I do not recommend to install buildout locally although it is possible, just use the one bootstrap downloads.

I must admit that buildout is not the easiest solution but its really powerful. So learning is worth time.

UPDATE 2014-05-30
Since It was recently up-voted and used as an answer (probably), I wan to notify of few changes.

First of - buildout is now downloaded from github https://raw.githubusercontent.com/buildout/buildout/master/bootstrap/bootstrap.py

That hyde project would probably fail due to buildout 2 breaking changes.

Here you can find better samples http://www.buildout.org/en/latest/docs/index.html also I want to suggest to look at "collection of links related to Buildout" part, it might contain info for your project.

Secondly I am personally more in favor of setup.py script that can be installed using python. More about the egg structure can be found here http://peak.telecommunity.com/DevCenter/PythonEggs and if that looks too scary - look up google (query for python egg). It's actually more simple in my opinion than buildout (definitely easier to debug) as well as it is probably more useful since it can be distributed more easily and installed anywhere with a help of virtualenv or globally where with buildout you have to provide all of the building scripts with the source all of the time.