Just when you thought that the Windows Home Server team had crawled under a rock and died, they very suddenly and unexpectedly release announce a public preview of "Vail," the next (Windows Server 2008 R2-based) version of the product. Neowin has the scoop about the public release (though I can't actually find it for some reason):

"Vail” is the version 2 release of Windows Home Server based on Windows Server 2008 R2. Vail provides simple file sharing, remote access, home computer backup, expandable storage through Drive Extender, and media streaming both inside and outside the home. Vail also contains an application catalog and product-wide extensibility model so that new services such as anti-virus, online sharing, and home automation can be seamlessly and easily added to the solution. Vail will be available pre-installed on systems by OEM partners, and a standalone software package will also be available for those who want to build their own systems.

Vail supports a number of Windows 7 technologies including "PlayTo" DLNA support to stream digital media to DLNA enabled devices. HomeGroup is also supported allowing simplified file sharing. Vail also includes Remote Streaming using Silverlight. Users can access their media remotely over the internet, anywhere. MPEG-4, 3GP, H.264, ADTS, AVI, MPEG-2, AAC, MP3, LPCM, MPEG-1. AC3 should be supported in RTM. MPEG2 and AC3 support are not available in this version, but are planned to be supported in the released version.

Vail is 64-bit only and requires 1GB of RAM or more, and minimum 160GB hard drive for installation. More information is available over at Microsoft's Connect site or the "Vail" Public Preview beta forums.

Update: It looks like the Vail preview has been announced but not yet released.

Update 2: The Vail public preview is now available.