Even before we released the Guidance Automation Toolkit, I knew it would be pretty difficult for a lot of people to work out what this was for until we had some useful guidance packages available. The plan is that many (even most?) patterns & practices deliverables will ultimately use guidance packages as the primary method for people to access them, but it will take some time before we get to this point.
In the meantime, you may want to check out a cool use of GAT: the NUnit Converter, developed by NUnit creator Jim Newkirk. This is a guidance package which automates much of the work in converting unit tests from NUnit to Visual Studio Team System. Whether you need to convert unit tests, or you just want to learn more about GAT, this is definitely worth a look.
And while we are talking about GAT samples, make sure you look at the GAT Hands On Lab that we developed for TechEd. It's hosted on GuidanceAutomation.net, which is a cool new partner site with lots of information and samples about GAT. Enjoy!