Actually, that is one thing I'm keeping my eye on. Now with OSX natively supporting USB 3.0 with the new Macbook models, I think it's just a matter of time till we see more Mac compatible USB 3.0 cards. If this happens, I see throwing one in my MP to get a little more life out of it.
These no good? http://www.lacie.com/products/product.htm?id=10493