The one 3.0 feature that I'm most excited about: Renderscript.

Renderscript in Android 3.0 is a stroke of genius. Basically it's a runtime (and simplified) framework for drawing 3D images and animating them in applications without the need to know more complex 3D APIs (eg. Open GL). The end result? 3D that's accessible to the lay programmer and vastly improved productivity for the experienced developer.

Why is this great?
A scripting language means quick testing. Without the tedium of the compile-test cycle *and* forgoing the necessity for diligent planning and design before implementation, a scripting framework allows developers to consider the 3D UI as an afterthought, to spruce up apps presentation (eg. adding a 3D wall of images to a once flat thumbnail UI).

Simplified syntax for simpler 3D. A script means simpler implementation. This is potentially a huge productivity booster and opens the world of 3D interfaces to every day programmers, or those just looking to dabble and experiment. Seasoned programmers will likely balk at this solution, but the one thing I've learned is this: don't underestimate the power of simplicity. Simplicity opens doors that remained closed for so many people and provides an entry point for exploration. One great example of this is Ubuntu.

While I fully expect Renderscript to be overused by many. I have faith that certain developers will use it very well and craft enlightening new UIs with outstanding performance.