General
Audio output device can now be switched while playing songs
Official support for OSX!
Improved unicode support
An option has been added to disallow playback while another song is playing
Linux: UDisks/UDisks2 support
Covers: cover manager improvements, saving to disk
UI
Playlists can be shown in multiple panes
The left tab panels are now closable
BPM counter plugin has better UI integration
Enhanced smart playlists
Create playlists based on other playlists
Support for filtering over 20 different tag types
Plugin
A simpler plugin API is available (but the old one still works!)
Plugin manager doesn't show users potentially broken plugins anymore
New plugins: console, Icecast Radio, lyricsmania, mono output, playlist an...