The feature they previewed was called Battery Historian. According to the presenter, there should a be a definitive improvement in battery life for the Android

The feature they previewed was called Battery Historian. According to the presenter, there should a be a definitive improvement in battery life for the Android "L" release. They've been using it to optimize Android and the Google apps. Hopefully people will no longer have to use all sorts of crazy hacks to because they suspect Maps/Location services is causing wakelocks.