WOW, I didn't realize how much I left out, when I asked my question. Let me fill in more details.

The Windows Phone development I want to do is for myself, only. I do work as a professional software engineer, but where I work there's no chance of doing any mobile development for the foreseeable future. However, I want to get into this on my own, I have some ideas for apps I want to get into the Marketplace. i.e.: this is all on my initiative. So syncing with others isn't an issue. Source control is incumbent upon me.