A few hours ago Oracle made APEX 4.2 available for download.
If it's the first time you look at 4.2, you can read about the many new features. With every release I have to say the same thing... it's the best release ever :-)
Obviously mobile is a big topic in 4.2, but for me personally I like the integration of HTML5 and CSS3 the most. At OOW, OTN asked me about APEX 4.2 and what I liked... there are so many, but the support for Responsive web design is the "key feature" for me to create future applications in a declarative way. That interview was even done before Shakeeb's excellent presentation about Responsive Web Design and his nice video.
So go and download 4.2 and start playing with it in your own environment today!