According to this announcement, the new version includes:
+ Full support for Firefox (history and bookmarks indexing)
+ Support for the latest PDF file format (v1.5)
+ A redesigned user interface for Web searching
+ Improved handling of French, German, Spanish and Italian content
You can read our positive review of Copernic Desktop Search in SearchDay article: A New Player in Desktop Search.
Mamma.com recently announced plans to acquire Copernic.