Besides the fact that Steve Jobs showed off a Carbonized version of Combustion running on OS X a few months ago, I also was told by a Discreet rep just a couple of days ago that Discreet will be releasing a Carbonized version after March 24. He emphasized that they are waiting until they have the final, shipping version of the OS but he made it sound like it won't be too long.
I like Combustion but I don't use it nearly as much as After Effects and I'm stressed that Adobe hasn't announced whether AE 5 will be carbonized or not.