Well here's a surprise - Microsoft Live Mesh will bridge Windows and Mac.
Here are the system requirements for the Live Mesh software from the tech preview site:
Windows
- Operating system Windows Vista or Microsoft Windows XP Service Pack 2
- Processor 800 MHz or higher
- Memory 1 GB or more of RAM
- Hard drive 25 MB of available hard disk space
- Browser Microsoft Internet Explorer 6 or later, Firefox 2.0 or later, or Safari 3.0 or later
- Internet connection Broadband Internet connection
- Display 1024 x 768 minimum display size
Mac
- Operating system Mac OS X version 10.5 (Leopard) or later
- Processor Intel
- Memory 512 MB or more of RAM
- Hard drive 25 MB of available hard disk space
- Browser Safari 3.0 or later or Firefox 2.0 or later
- Internet connection Broadband Internet connection
- Display 1024 x 768 minimum display size
Also note how Safari is supported. Hmmm, so Microsoft is breaking down walls between Windows and Mac. Interesting.