I recently joined a software development project that involves not only myself and other internal Microsoft employees, but a partner and a customer as well. We are building a hybrid solution that uses assets on premises as well as Windows Azure for processing. When we put the team together we picked a methodology (Agile) for the project (we use multiple methodologies at Microsoft - whatever the project needs) and then we started talking about Source Control.
We’re all comfortable with various tools for check-in-check-out, branching, and so on. We have all used GIT, SVN, and TFS. Some of us have even used Source Safe in past, but that’s another post. 
Each company has a full set of Source Control systems in place. But using each other’s systems requires logins, firewalls and the like - so we decided to use the TFS Service Preview to run the entire project from “the cloud”. Here are my experiences with that.
The process was really simple. In fact, we talked about using the cloud TFS in the first SCRUM, and the team was working from the Work Items list that afternoon. The original account login provides a web interface to allow people to join the team. Each of us happened to have a Live.Com address, so we just invited those addresses to join and they got a link, like this:
projectname.tfspreview.com
I’m using Visual Studio, and it’s a requirement for TFS preview to have SP1 installed, and this patch: KB2581206
From there, I opened Visual Studio and navigated from the main menu to Team and then Connect to Team Foundation Server. I’m given this menu:
Selecting port 443 and HTTPS (for security) and then ensuring the lower link has the “tfs” appended as the location, I opened the project.
(This VSTS screenshot is of a project I did in my University of Washington class I teach - I never show client code or names in a blog post)
From there it’s a normal set of operations. Right now the preview doesn’t have some things I’d really like, such as an automated build or some of the testing tools, but you can read this blog entry to learn more about the entire sign-up process, and what the team has planned.
Each day I log in to the project, and I’m given this new sign-in option:
I click the option, and I open the environment, hit My Work Items query, and get to work. All in all, a seamless - although basic - experience. The speed at which we could set up and work on a project was really sweet. It’s remarkable how un-remarkable this is - I just do my work each day, everything is running and backed up in the cloud. I think that’s the point.