<p>are there any free Team Foundation Server sites we can use for our <em>private</em> development? Please don't say CodePlex (which I love) because that means the code is all opensource.</p>

<p>Lastly, I also understand that some people might raise the issue of having their private code hosted somewhere by people they do not know, etc.. so please don't raise any security concerns.</p>

<p>I'm guessing there are no free services because of licensing reasons?</p>

I would find it doubtful that there would be a free one.  Team Foundation Server was very expensive for us to implement so I would be surprised if someone was hosting for free.  Other than the CodePlex type options.
There are services where you can pay per user per month like
this one
or
this one
>
I find it doubtful you will find free though.