The Team Foundation Service is now live.
If you have tried the preview version, you'll eventually have to change the URL to the service. The new URL is https://yoursitename.visualstudio.com:443/defaultcollection
You'll still need to install the hotfix mentioned here, if you are new to the service.
You can learn more about the service here: https://tfs.visualstudio.com/
The service is to some extend free to MSDN subscribers.