Arthur, the Norton engine's rotary ("Revolutionary") valve was the the Cross Valve.
The biggest problem at the time was the severe temperature gradient between inlet and ehaust ports on the rotary portion. It was wery difficult the ensure proper lubrication and sealing.
With modern technology and materials, I believe that Ceramics could be used to combat the temperature and expansion/sealing difficulties.
Currently, with any sort of rotary valve the nature of the relatively high speed rubbing syndrome tends to consume the lubricants and this leads to wear and unfriendly emmission problems.
The same applies to the Aspin rotary valve featured in Malcolm's link.
When you think of the high temperatures attainable with domestic non-stick frying pans and the modern use Nikasil cylinder bores, I still believe that there is a lot of scope for investment and development of the rotary valve AND the Wankle Potary Engine.