The Suzuki Crosscage, scheduled for an appearance at the 2007 Tokyo Auto Show, may be powered by a hydrogen fuel cell, or high pressure air, possibly fuzzy kitten dreams - who knows. Details are light, but it does have a monoshock up front though, and that's pretty radical. We'll be following up on this one since it's got super engineering potential written all over it.
Monoshocks really aren't too crazy. If you think about it, McPherson struts in cars are similar in that they are loaded on one side. The main thing is to prevent side to side motion, but the moment is fairly small because of the narrow front tire. The deflection is directly up into the shock, which makes things a lot simpler (and stronger) since there's no linkage to worry about.
The other concern is fork flex, which you want to be symmetric since a bike leaning into a turn uses frame fork and swingarm flex as suspension.