Just reading planet and mailing lists these days...:

git filter-branch --subdirectory-filter directory refspec
git clone --no-hardlinks /tmp/gtk2-perl Gtk2-SourceView.git
git tag -f -d ${TAG}
git filter-branch --subdirectory-filter Gtk2-SourceView HEAD
git reset --hard
git gc --aggressive
git prune
git-svn clone svn+ssh://username@svn.gnome.org/svn/modulename/trunk modulename
git-svn rebase
git checkout -b mybranch
git merge --squash mybranch
git-svn dcommit