The CodePlex team has announced the CodePlex Source Control Client on their blog today.  There is a beta, which I recommend you download if you use CodePlex for source control.

I have known about this effort for a while, and was approached as an internal alpha tester (in my copious spare time).  I have used this against internal servers for testing, and I have been quite happy.  Of course, it is a beta, so there will probably be an issue or two to work through.