Please if you don't mind, add these to the list.
1. Abandon the "active" zone concept for remote TCP/IP control. I need complete and independent control of the zone for which I am listening to, no matter which zone the console happens to be looking at. Of particular interest are library and cover art browsing I know there is already discrete control of playback (pause/play stop etc).
2. Database synchronization. This has already been mentioned, but I will restate; I need to be able to synchronize databases between multiple LAN and WAN connected music servers running Media Center. The streaming "media server" option is not a viable solution for this problem. I need to have 2 or more instances of Media Center running in a networked environment where both / all systems can simultaneously add tracks to a common database. Even an option to replicate / merge once a day would be completely acceptable.
3. YADB lookup is still well below par compared to CDDB, expecially when talking about cover art. Although not a real show stopper, this makes this otherwise incredible paltform look somewhat hobbyist compared to other solutions.
4. WAV file tagging. Uncompressed wav file format continues to be the common denomenator when it comes to sharing full quality files among various systems. MMJB has done this for years.