Last week I built a new custom MSBuild task that keeps the CodePlex repo up to date with our internal TFS. Each time the CI Build runs any changesets are retrieved from TFS and each change that is related to the Community Edition code base is then pushed through to Codeplex along with the comments. Each type of change such as Edit, Add and Delete is handled so that you can be sure the code on CodePlex is exactly what we are using internally.
Enjoy!