VMware, a leading developer of virtualization technology, will offer an Intel-based Mac OS X version of their, while  for Intel-based Macs, the two firms announced today during WWDC. Apple provided no new information in public statements about  with next spring's release of Mac OS X 10.5 Leopard. (Microsoft's FAQ on Intel support was not updated at this writing; we received word via press release.)
In general terms, virtualization software enables a computer to run one operating system parallel with another; for instance, virtualization software for Mac OS X might enable a user to run Mac OS X and Windows XP (or a distribution of Linux) side by side without switching from one to the other via rebooting. Robert Movin covered in TidBITS-825, and  in TidBITS-834.
VMware expects to release a beta version of their product "later this year," and to signal interest in being part of that testing. More significant than VMware offering competition for running Intel-based operating systems within Mac OS X is the firm's plan to provide interchange support for disk images created on all platforms with each other. This support means that a virtual machine running on VMware's Windows XP client edition could be copied or mounted via a fast network shared volume on a Mac and run without conversion. VMware claims four million users.
Microsoft's Macintosh Business Unit ended months of speculation about whether the division would update Virtual PC to work with Intel-based Macs. The company said it would have to start from scratch rather than revise current software, and stated that "alternative solutions" offered by Apple and others would do the trick.
 their Parallels Desktop for Mac package for running Intel-based operating systems.