I accidentally stumbled across CAL++ as well. Sounds like a sweet deal. Unfortunately, I couldn't easily build pyrit under windows so I have to give in with the idea for now. And I'm not familiar with C at all.
80% improvement sounds awesome and it just might work. Even a 10-20% improvement to hashing would be major. I think you could get quite a few donations for porting poclbm to use CAL++ instead of the OpenCL wrapper.
I hope someone will look this up !
I'll look more into this today, since you've actually heard something about it. Unfortunately, there is no support for CAL++ in Windows. People trying to get it to work in cygwin can get CPU stuff to work, but I haven't read anything about successful GPU. So this would be a Linux only thing.
As for AMD dropping CAL support, I couldn't find anything about that online. I searched and somebody mentioned it back in 2008, but they failed to produce any official support to their statement. If you could grab that information, that'd be awesome.
The good thing about CAL is that it supports Radeon 3xx0 series cards. That would be a big improvement for some people, because I have a spare laptop with a Mobility Radeon 3650. OpenCL doesn't work on these cards.