Android's L release is going to bring about a ton of new changes and improvements, and they took time to talk about a few of the most important today. That includes a new default runtime, improved graphics, and improved battery life.
ART is now the default runtime
We actually saw this coming, but it's now confirmed. ART brings twice the performance over the current runtime, Dalvik. It has been available as a preview for KitKat, but is becoming the default (and from what I can tell, only) runtime in the L release.