Actually, hardly anything has release velocity, these days. It didn't turn out to be that useful of a feature (hard to control) and next to nothing allows you to do anything with it...

Just what WOULD anyone use it for? Altering the release time of a sound? Trust me on this one (I've used keyboards that had it in the past), it is VERY hard to train yourself to not only hit the keys with the correct degree of force, but now you have to learn to LIFT your fingers just so, as well. This one gets relegated to the 'good idea, bad idea' bin, IMO.