I agree about the 661 vs Dianese. I have a 661 suit (upper body inc. shoulder, elbow, back, chest, lumbar) which is great, except that I already fill my jacket out enough that wearing the thing makes me look like a fully kitted linebacker!
I have a pair of Dianese pants with knee pads in them which are pretty awesome. They also keep you warmer when kneeling in the snow.
And finally, Fox are producing a MotoX knee brace for this season under the name PodMX. I used the final production prototypes a couple of weeks ago up at the snow, and for anyone with knee issues they are amazing. And for those just looking for protection, they are pretty damned good for that too, being made of full carbon fibre and designed for protection in high speed collisions when riding trail bikes.