It shouldn't be too difficult to add XBMC and Retorpie to a current raspbian image.
I tried it myself and I followed the following tutorials:
1. Installed a fresh Raspbian Image with Berryboot.
2. Installed XBMC with the following Tutorial: http://www.raspbian.org/RaspbianXBMC
3. Installed Retropie following the following Tutorial: http://blog.petrockblock.com/2012/07/22 ... pberry-pi/
XBMC installed just fine, but I had to give up, because I was unable to autorecognize USB storage devices that I connect automatically. Having to mount manually was too much hassle. That might be an easy task for someone who is familiar with Linux, but an Linux Idiot like me can only follow guides and enter commands exactly as instructed.
WIth Retropie, the installation failed a t some point with error messages indicating, that all dependencies are not met. Again, as a Linux idiot, I can't help myself, but someone else might be easily overcome that error.
If someone works with linux regularly, getting XBMC and Retropie on the same system running schould be doable within a day.
A Image would save us a lot of hassle.
I would do it myself and release a image, but unfortunately I lack the linux skills for it.
I hope someone can carry on the good work on this Image.