Take a blackberry and try typing a sentence without looking at it. That's what it feels like. I had the same question and even thought about prototyping a hardware, but thank god I tried pseudo experiments before doing that.
Laptop keyboards work without looking because the keys are large enough that once you lock in your two index fingers onto the little bumps on F and J keys the rest depends on your muscle memory, but that's not the case for mobile devices.
But what really seals the deal is even if you somehow manage to pull off the haptic feedback part, you're trying to make people relearn an entirely new way of typing it's almost like learning a new keyboard layout. Just like dvorak keyboard never caught on even though it was much more efficient, unless there's a significantly next level benefit, it will be very tough to get people to use them.
That's why I had the same idea and played around with several ideas on this, and then decided that it wouldn't work. The benefit was not worth all the hassle.