File-level storage pooling vs cluster-level in WHS.
Supports Linux and Windows machines.
Copies over SMB/rsync, thus will require whole HDD to be shared in order to back up the entire disk (alternatively only directories that need backing up can be shared).
Web interface to view logs, configuration, current status, and can also be used to initiate or cancel backups, and to browse backed up files and restore them.
Restoration can be done either over SMB or with a downloaded ZIP/Tar file.
Emails can be sent if a machine hasn't been backed up in a while.
Can use VMware Server along with various Windows ISOs from MSDN-AA to do any necessary Windows testing
File Sharing (SMB)
Multiple:
Samba for SMB/CIFS.
NFS for other Linux clients.
iSCSI maybe for illusion-of-local-disk on clients. (Guide)
Apache + PHP for HTTP/HTTPS, giving remote file access. Write my own or use pre-made software?
Media Streaming (UPnP AV Server)
MythTV
Seems overkill just to share media to Xbox etc.
uShare
Less overkill, if it works. Xbox 360 is able to see the music, but not play it.
Power Management
Spin down disks? How will LVM affect this?
hdparm's -S argument. “-S 120” for 10 minutes, “-S 240” for 20 minutes. Anything above that gets complicated, so read man hdparm.
SpeedStep support? cpufreq, but should be automatic. cpufreq has this bad habit of not actually changing the CPU speed and leaving it at its minium, from what I can tell.
DVD Ripping
FairUse Wizard under a Windows VM shouldn't be much slower (can only make use of two cores anyway).
A GUI'd Linux app no doubt exists.
As (probably) does a CLI app, but that could very well be painful to use.
A ripper that can put more than 2 audio streams in a container would be nice for, e.g. SG-1's 200. Also one that could extract more than 1 subtitle stream at once…
Other Considerations
Support audio output over coax S/PDIF. So a music server could exist with web and/or (preferably) non-web remote control.
Network streaming? Using Windows machines as PulseAudio clients (audio sources) is really horrible currently.
Bluetooth support? Not sure how far that could go, but could be interesting nonetheless.
Local internet access on phone?
Bluetooth media remote control for music player?
4+GB RAM. By recompiling the kernel, Physical Address Extension (PAE) can be enabled in the BIOS, allowing the operating system to address more than ~3GB RAM. Window Server also supports this, but most drivers do not, causing endless BSODs.