In many recent video games that have been published (mostly Sonic the Hedgehog games), I have seen that they are using this new(ish) system of motion blur. What it does is only blur the area around a single object instead of blurring the whole scene. I would love to see a script that could achieve the isolation and blurring of a single object, if that is even possible. (It would also be awesome if it was compatible with ATI GPUs)
This would be a very useful script, you could apply it to the objects in your game that will be moving fast, essentially isolating the objects that need blur. This would probably not be nearly as resource demanding as blurring the whole scene would. 
If anyone knows of a script like this, please link it in your reply!