Yep, the repository is public and a big chunk of this public data is accessible on BigQuery for anyone to query and analyze.

Ilya Grigorik and myself just gave a talk at Strata[1] on interesting analysis and visualizations that people did with the GitHub Archive as part of the GitHub data challenge[2].

We'll post a link to the talk soon. We announced during the talk that BigQuery will soon (in the next day or two) have an archive of the GitHub public timeline from February 2011 to now. I can't wait to see what people do with it!

[1] http://strataconf.com/stratany2012/public/schedule/speaker/2...

[2] https://github.com/blog/1162-github-data-challenge-winners