inter-operating system communication

They run their own OS's which are radically different to all forms of Windows.

To do what you want to achieve here you will need the Scrabble game written for the OS of the device you are using which can then be interfaced with a Windows PC to get your required result maybe.

Porting any program from it's native platform to another isn't either easy or cheap so the easy answer here is that maybe you would find things easier waiting for Windows 8 to become available and then buy a Tablet Device that Runs Windows 8.

I'm not sure of how well it will work as Windows 8 is still very much in the Pre Beta Stage of Development and while it currently appears to work well with Touch Screens by the time it reaches Release to Manufacturing [b]RTM[/b] it will be radically different and may not suit Tablet Platforms or the then available hardware. But it may work perfectly to.

Col

Perhaps a Flash game? (There goes the iPad option.) Is it hosted on a web server, or are you playing a locally installed game in a peer-to-peer manner over a network?

You'll have to describe how the game uses a network a little, and/or just point us to the actual game itself. There shouldn't be any OS network communication issues in most cases, as networks are generally OS-agnostic.