The next major release has finally reached stable state and is now available for download. The most important improvement since the 0.5 line is certainly the full-featured address book which now provides a smart interface to manage rich contact information including photos. A brief description of all new features was posted here: http://lists.roundcube.net/mail-archive/announce/2011-08/0000002.html
More... (http://sourceforge.net/news/?group_id=139281&id=303670)