The git-svn tool is a simple conduit for changesets between Subversion and Git. It provides a bidirectional flow of changes between a Subversion and a Git repository.
The latest msysgit distribution of Git for Windows (version 1.6.1 preview 20081227 at the time of this writing), does not come bundled with the the git-svn tool. This can be installed on Windows using the Cygwin distribution of Git, however.
Download and run the Cygwin setup program, and install the Devel -> git and Libs -> subversion-perl packages.
You can add the Cygwin bin folder (e.g. C:\Cygwin\bin) to your path to make running Git easier.
Try running “git svn” at a command prompt to see if things are installed properly. You should get a “fatal: Not a git repository (or any of the parent directories): .git” message. If you get a message like “*** fatal error – unable to remap C:\cygwin\lib\perl5\site_perl\5.8\cygwin\auto\SVN\_Core\_ Core.dll to same address as parent(0×260000)”, then try applying this fix.
I kept getting an error like “Can’t write to .git/svn/.metadata” when I ran “git svn fetch” and the revisions were being fetched, but I would just run this command again and it would successfully continue fetching the next revision.
Also, if you want to work with GitHub using SSH, then you need to take some extra steps to do this. See this page and the links inside for guidance.