Q: what does this directory means?
A: http://vignatti.wordpress.com/2010/09/02/x-census-for-1-9/
   http://vignatti.wordpress.com/2011/02/28/x-census-for-1-10/

Q: How you got all this info?
A: something like this, using gitdm:
   $ for i in `ls`; do cd $i; git log -M -p --after="2010-08-20" --before="2011-02-25"; cd -; done | ~/git/fdo/gitdm/gitdm -l 10 -c ~/git/fdo/gitdm/sample-config/xorg/gitdm.config-xserver -b ~/git/fdo/gitdm/ > someoutput.txt