The most recent Skype version usable is 18.104.22.168 from the Fedora repository.
Follow the instructions at: the OLPC news forum.
The only thing that doesn't work is the video out, that is, when you want to send your webcam video signal out to others with the video call.
I'm working on this by:
- Modifying the gstfakevideo sources and trying to understand why some ioctls fail
- Trying to upgrade the linux-uvc module on the XO, by grabbing the kernel sources and compiling linux-uvc.
I will let you know… :)