Ever since Microsoft announced they will be {... messing up ...} their Windows Home Server product
I'm really pissed off about this. I tried one of the early previews of WHS "Vail", and it looked good enough to persuade me to migrate off of a Linux server, what with the drive extender stuff and the ability to back up your other Windows PCs.
Now that they've dropped the drive extender stuff, and completely rejected the possibility of including Windows Media Center functionality, there's just nothing interesting or compelling about the product at all.
I might as well just use straight Windows 2008 R2 server, or stick with the Ubuntu server that I've already got. The "greyhole" stuff looks pretty good for disk extender use -- I'm currently using LVM, which isn't exactly user friendly, and doesn't (?) do duplication. I do backup of the server using rdiff-backup, which works pretty well. Backup of the PCs is by the simple expedient of telling the wife to save her files on the server. "Streaming" is accomplished via SMB to a Windows Media Center PC plugged into the TV.