Many of today's high-end cell phones are powered by Microsoft's Windows Mobile 5 operating system, which meant that Mac users couldn't synchronize their contact information and other data. Now, the release of Mark/Space's The Missing Sync for Windows Mobile 2.5 jumps over that hurdle. The new version ties into Apple's Sync Services under Mac OS X 10.4.7 or later for addresses, calendar items, and to-do lists, and it offers specific support for synchronizing data with Microsoft Entourage. It also includes plug-ins for iTunes and iPhoto to transfer music and photos to the phone, as well as the capability to mount the device on the Desktop for direct file transfer. A new toolbar in version 2.5 offers quick access to commands, including an easy way to install Windows Mobile software. The Missing Sync for Windows Mobile 2.5 is a free update for owners of version 2.0 or later, or as a $40 electronic download (or $50 CD) for new users. Upgrades from older versions or some other eligible products cost $20.