There are many questions people ask on a regular basis as to why Git was chosen, and why you should also choose Git.
Why Git at all?
A DVCS is required. SVN 1.5 is a step in the right direction, but is just an extension of the old SVN behaviour with some shiny changeset capabilities.
Why Git at Codehaus?
GitHub rocks. But do you want to tell users that your source code is off in some other 3rd party system?
Keep everything at Codehaus. Enjoy!
Why not something else
Email Russel Winder, he'll tell you