I would stay away from the rev A MBA at all costs. Personally, it's just not worth the trouble. Yes, Cool Book helps, and yes the software has gotten better from my original MBA, but I just don't think with ALL of the problems that the rev A MBA is the right path.
Look to the xBench marks between the models. The rev A MBA with 1.8 GHz and SSD performs WORSE than a rev B MBA with 1.6 GHz and HDD.
I have a rev B MBA with 1.86 GHz and SSD. The thing is lightning fast. Boot ups and application opening and even opening large files is extremely fast. It makes my MBA feel much faster than my unibody MB or MBP.
It is perfect for portability. Yet it is powerful when working with a 24" ACD. It really meets my all around needs and wants of a Mac. It is light and beautiful.
The rev C could be a long wait. The rev B is so very good that there is no real reason for Apple to change right now... maybe a thin war with Adamo, but that is not a good thing. Apple does not have a new CPU to move to as the SL9600 which is the next same series chip is not out yet. The 256 GB SSD in 1.8" form is not available yet. There will be some waiting, although it has been 4.5 months. I would go with the rev B and be happy. Good luck.
No matter which rev B you go with, you are going to get a great computer. Get ready to be amazed. Go MBA!