The developers at Roundcube finally decided to release version 0.1 as a stable release. I’ve been using the release candidates without problems for many months. A new thing I discovered is the installer pages which help you to setup your PHP and Apache settings to make it work correctly. Another new thing is the inclusion of TinyMCE to allow you to create HTML mail.
If you want to you can download the new version and start installing/upgrading. Download it from here.