Google is finally showing developers what an Android app should look like. Android Design is Google's freshly launched style guide for Ice Cream Sandwich. It outlines everything developers should do to make a high quality app that "fits in" with the rest of ICS.
Most of the big stuff is covered: Icons, color swatches, grid layouts, writing style, touch feedback - it's beautiful. Apps are normally all over the place, it will be really nice to see some consistency.