I have looked and did not see any option that would let you post notes about a song or album. I know that sometimes when I am listening to music, I have different emotions or thoughts that I would love to tag to the music and search to find the notes to help remember the occasion. I know it would help me find things quicker when I am looking for that one song for the mood I am in.
You're probably aware of the 'Comments' tag, but for short notation the 'Grouping' tag' (if not already being used), could would be useful.
I use it all the time to store track: rating, holiday, party, chill, wife, oldies, guitar solo, dj intro, jingle, only me, etc.