Exchange support in the iPhone has been rumored almost as long as the iPhone itself was rumored to exist. Much as the iPhone turned out to be real, so has ActiveSync on the iPhone. Microsoft released an interview with Terry Myerson, corporate vice president for Exchange, which includes a very interesting tidbit. Mr. Myserson says that Apple and Microsoft were in talks about licensing ActiveSync before the iPhone was announced. Furthermore, he was in daily contact with Apple VP Phil Schiller (when Schiller wasn't making up Apple rumors, of course) for two weeks while they set the details of the agreement between the two tech giants.
This isn't a revelation, since it stands to reason that a company in the business of selling a smart phone and another company in the business of selling technology for smart phones would work together but it is interesting nonetheless.