I just got the following email from Havok, announcing Project Havok is now available for download.
If you've never heard of it, or Havok for that matter, Project Anarchy is a collection of game developer middleware, being made available completely free for mobile developers.
The most likely piece of Havok tech for you to be familar with is their physics engine, which is basically ubiquitous in the industry. The package also includes an AI library, the Vision Engine, which is a 3D engine similar to Unity or UDK, content pipeline tools for most 3D packages, etc...
If you are looking at doing mobile game development, especially advanced 3D work, you really need to check it out.