I saw a writeup on an interesting new transmission design in the SAE magazine being developed by an R&D company in the UK named ZeroShift.
Basically, the way it works is that gears are linked together by sliding "bullets", which can lock gears together in one direction, but if one gear outspeeds the other, the bullets disengage. These sliding bullets would replace the synchronizing components on a manual transmission. It is hard to describe, but the animation here illustrates it.
Supposedly, this technology allows very smooth quick shifts, and eliminates many parts of current transmission.
ZeroShift is testing a prototype unit which is installed in a V6 Mustang.