Google initially released its Material Design guidelines in July and designed it as a feedback mechanism from developers to refine the initial aesthetic and look of Android 5.0 when it was unveiled in February. Today, it has updated these resources and guidelines as the release date nears.
So today, together with the Android 5.0 SDK that was just made available by Android Dev for download, Google has published updated guidelines and resources, taking in the feedback of the Android community and tweaking the look of Material Design to what it is now.
The resources include sticker sheets in PSD, AI and Sketch formats, an updated icon library, new color swatches, among others to help developers have an idea of what look Google is shooting for in Android Lollipop. Specifically, the new system icons sticker sheet contains the new look of the icons that can be used across different apps for different purposes such as media playback, communication, connectivity, and so on.
If you are an app developer, best to take a look at these new guidelines to get ready for the upcoming release Android Lollipop, which Google will choose to push across all possible channels. The new devices that will first carry Android 5.0 will come out in November, so there are just a few weeks before that totally happens.