Windows home server is an upcoming operating system announced by Microsoft at the 2007 CES. This is intended for homes with multiple PCs and will support file sharing, automatic backups, terabytes of storage(!) and connectivity to other devices such as Zune and Xbox.

Check here for some of the prototypes,

Over at the Microsoft press tent at the Consumer Electronics (CES) Show, Microsoft is showing off a few protypes of its just-announced Windows Home Server product.
Although there were rumors circulating over the past month that Windows Home Server would be based on Windows Vista, that’s not the case, said product director Steven VanRoekel.

More Info
Windows Home Server Homepage
What is inside Windows Home Server?