Are there any other good alternatives to zc.buildout and/or virtualenv for installing non-python dependencies?
Setuptools may be capable of more of what you're looking for than you realize -- if you need a custom version of lxml to work correctly on MacOS X, for instance, you can put a URL to an appropriate egg inside your setup.py and have setuptools download and install that inside your developers' environments as necessary; it also can be told to download and install a specific version of a dependency from revision control.
That said, I'd lean towards using a scriptably generated virtual environment. It's pretty straightforward to build a kickstart file which installs whichever packages you depend on and then boot virtual machines (or production hardware!) against it, with puppet or similar software doing other administration (adding users, setting up services [where's your database come from?], etc). This comes in particularly handy when your production environment includes multiple machines -- just script the generation of multiple VMs within their handy little sandboxed subnet (I use libvirt+kvm for this; while kvm isn't available on all the platforms you have developers working on, qemu certainly is, or you can do as I do and have a small number of beefy VM hosts shared by multiple developers).
This gets you out of the headaches of supporting N platforms -- you only have a single virtual platform to support -- and means that your deployment process, as defined by the kickstart file and puppet code used for setup, is source-controlled and run through your QA and review processes just like everything else.
I am a member of a team that is about to launch a beta of a python (Django specifically) based web site and accompanying suite of backend tools.  The team itself has doubled in size from 2 to 4 over the past few weeks and we expect continued growth for the next couple of months at least.  One issue that has started to plague us is getting everyone up to speed in terms of getting their development environment configured and having all the right eggs installed, etc.
I'm looking for ways to simplify this process and make it less error prone.  Both zc.buildout and virtualenv look like they would be good tools for addressing this problem but both seem to concentrate primarily on the python-specific issues.  We have a couple of small subprojects in other languages (Java and Ruby specifically) as well as numerous python extensions that have to be compiled natively (lxml, MySQL drivers, etc).  In fact, one of the biggest thorns in our side has been getting some of these extensions compiled against appropriate versions of the shared libraries so as to avoid segfaults, malloc errors and all sorts of similar issues.  It doesn't help that out of 4 people we have 4 different development environments -- 1 leopard on ppc, 1 leopard on intel, 1 ubuntu and 1 windows.
Ultimately what would be ideal would be something that works roughly like this, from the dos/unix prompt:
$ git clone [repository url]
...
$ python setup-env.py
...
that then does what zc.buildout/virtualenv does (copy/symlink the python interpreter, provide a clean space to install eggs) then installs all required eggs, including installing any native shared library dependencies, installs the ruby project, the java project, etc.
Obviously this would be useful for both getting development environments up as well as deploying on staging/production servers.
Ideally I would like for the tool that accomplishes this to be written in/extensible via python, since that is (and always will be) the lingua franca of our team, but I am open to solutions in other languages.
So, my question then is: does anyone have any suggestions for better alternatives or any experiences they can share using one of these solutions to handle larger/broader install bases?