The statistics synchronization for Amarok 2.7 is the result of this year's Google Summer of Code. As far as the feature, it's described as, "Amarok will work hard in the background from that point to make sure your ratings, first/last played times, play counts and labels are synchronized between all participating collections (Local Collection is included by default) and won't disturb you unless there's a conflict. If you have Last.fm plugin configured, tracks recently played on your iDevice will be automatically scrobbled to Last.fm as part of the synchronization."
For many more details on this Amarok 2.7 feature, there is a lengthy blog post by the developer responsible for statistics synchronization.
Another new feature to Amarok 2.7 is the improved Amazon MP3 downloader that's integrated into the KDE application.
The final release of Amarok 2.7 is tentatively planned for 17 December while the beta should be released at any time.