In case you didn't know, Unity provides the glue that makes a considerable amount of iOS games work. It's a game engine, development environment, and multi-platform publishing tool rolled into one easy to use package. (You can read all about it here.) The magic behind Unity is what brings the world of Aralon [$4.99] to life, and what allows you to level up in Order & Chaos Online [$6.99]. Similarly, it's what allows Gameloft to take Order & Chaos and seamlessly turn it into a Facebook game. The engine isn't limited to 3D either, it's what's behind fantastic 2D platformers like Max and the Magic Marker [99¢] and too many other games to list.
Recently, Unity 3.4 was released which brings a whole boat load of new features, functionality, and other tweaks. So many, in fact, that it's hard to pick out which to highlight. Personally, I'm excited for better water effects, because who doesn't love water effects? Also, finally having gyroscope support is going to be great. The best part about these kind of engine upgrades, is that most of the tweaks and enhancements are essentially "free" just as part as developers upgrading to the new version, and testing to make sure that nothing breaks in the process.
If you're a Unity developer, download 3.4 and give it a shot. If you're a gamer, keep an eye out for upcoming Unity titles that benefit from the mile long feature list of the 3.4 upgrade.