Today, May 7 2014, was planned as release date of Qt 5.3. But release plan was updated and tomorrow, May 8 is announced as the date for release candidate and final release should be ready as soon as May 20.
Full release plan for Qt 5.3 is available here:
There will be a lot of new features and bug fixes available in this version of Qt. Major enhancements in Qt print support and WebKit modules should be done. Qt supports new platforms also now: Windows RT, Windows Phone 8.