Looks like Mac users are beholden to Microsoft for Windows emulation for the foreseeable future:

“Recent management changes at FWB has led to a major evaluation of the status of development work including Realpc. ‘Since taking over F.W.B. software on July 17th one of the first priorities was determining the status of all development work on going by FWB.’ explained Marko Kostyrko, FWB’s new CEO,” states the FWB website.

“He continued, ‘The previous management had made claims in press interviews and on the company website regarding the status and upcoming release of RealPC OSX claiming it was in late beta and about to be released. After more thorough investigation and interviews with the previous staff, we have found that the development had not formally been started, and it appears not a single line of code has been written. FWB has not to date even received the source code upon which any development would as the foundation to build a new RealPC for OSX. I am sorry to have to admit that apparently the company has been a party to vaporware when it comes to the claims regarding RealPC,'” states the FWB website.

“In reviewing the status, it was determined that the development cost including licensing fees made the project unattractive. Therefore, the new management has determined that it is not in the best interests of FWB to go forward with the development of RealPC. Honesty and openness with the user base is a cornerstone of the new management team. We are developing software to return FWB Software to it’s historic position as a leader in disk utility software,” states the FWB website.

Related MacDailyNews article:
Bill Gates to Steve Jobs regarding Virtual PC: Checkmate – Feb 19, 2003
Microsoft confirms VirtualPC incompatible with Apple’s G5 – August 27, 2003