While I agree MC needs to add some polish to it's current feature set, I have to think that where I'm looking at going with MC is far beyond Audio, Video, Images.
I'm already trying to bend MC to my will for some things (Recipies, Wine Reviews, Live Recordings, etc), but would love it if I was able to check mine, my wifes, our joint calendars from MC, look up our respective contacts, and sync our phone with data (Contacts, Recordings, etc) from our KitchenPC or HTPC (Ideally over Bluetooth or Wireless).
To be able to automatically import categorise media recorded on mobile devices, and even upload to Pix01, YouTube etc would be very nice.
If anyone has ever used HP's TouchSmart environment, you'll have an idea of what I'm thinking of - although it is inferior in every other way..
(Speaking of touch... is MC preparing for multitouch at all? Its coming -well duh- and situations like Kitchen PCs will become more and more common I should think.)
I have to agree a notes functionality would also be awesome.
In summary, I'd like to see MC move throughout the house, not stay locked to the TV. I think a well developed and documented plugin system for Theater View will also be a huge boon in this regard.