I believe MUI can still be registered, except Stefan will send a generic key file instead of one in your own name. See sasg.com.
It's not a generic key file, it's the key file of somebody else. Always the same, the only one he has left as it seems.
Last I heard Stefan had completely abandoned computers and was off mountain biking the Alps, or some crazy thing like that. 
If it was only the Alps. Last time it was the Andes, acrosss the whole of South America:
http://www.alpenzorro.de/andix
