I have always had niggling issues with XBMC on a variety of distros, but finally (and simply) I have come across a solution that minimises XBMC so that I can work alongside it whilst it streams to my PS3.
The fix is a simple one; simply hit "\" when XBMC is loaded and the entire XBMC default screen become just another window with minimise, maximise and close present.
That's it! It's taken forever for me to find this simply fix, and now ensures that I am one step closer to fully converting to my current distro of choice, Xubuntu 12.04.
This in a nutshell however, is the primary problem with Linux and is in my opinion what is stopping Linux from gaining a strong market foothold. Simple, basic things like this which no doubt other users have fallen foul over, just get in the way of the Linux experience. Once you know how to navigate your way around the desktop though, it really is a much better experience.