What does heart icon next to album image means? I couldn't find documentation for it anywhere. I guess it's favorite button, but I cannot find play favorite songs either.
It's a rating system for songs. A hearted song means you like it and a broken hearted song means you don't like it. The software will play your hearted songs more often and your unrated songs less and your songs marked with a broken heart even less than that.
The heart is a like/dislike option for a song. If selected, it means you like the song. This like feature is very useful in zune software. It gives you the ability to create an Auto-playlist for liked songs.
NOTE:- you can't do this on phone; as creating, editing and deleting playlist is restricted to zune software only
The heart also allows Zune to automatically remove "Broken Heart" songs from your device automatically. In your sync setting on your Zune client, you'll see a checkbox for "Don't sync songs with (broken heart)".
I find it a great way to automatically get songs off my phone that I no longer like.