Hi there!
As we close in on PyCon 2012 this year I wanted to make sure everyone will be ready for the DevOps tutorial. The important things to have installed are Chef and Fabric, of course. Any kind of Chef install should suffice, on OS X you can just "gem install chef" or on Windows you can use the the MSI. Fabric can be installed via "pip install fabric". If you have issues installing Chef on older OSes you may need to update Ruby, which is easiest using rbenv. If you are able to run both knife --version and fab --version you should be all set for tools.
If you get an error about "HTTP Response 302 fetching http://gems.rubyforge.org/yaml" you may need to update RubyGems as well:
sudo gem install rubygems-update --source http://production.s3.rubygems.org/
update_rubygems
Also I will be using Amazon's EC2 cloud as the baseline for the in-class labs. Nothing specific to EC2 will be used, but you will need access to some kind of similar environment. If you are familiar with another cloud provider or Vagrant, you can check out the other supported platforms, but if you are unsure I would recommend just making an EC2 account in preparation for the class. If you have any questions about getting things setup you can reach me at noah@coderanger.net.
I will also be around the day before the tutorial and that morning for questions behind the registration desk.