This week's book giveaway is in the Agile and Other Processes forum. We're giving away four copies of The Journey To Enterprise Agility and have Daryl Kulak & Hong Li on-line! See this thread for details.
Yes. But how you do it depends on what you mean by curved buttons.
Generally, you use Drawables as a background to define a button's shape. For simple things you could use a Shape, but if you can use 9-Patch images to get more complex (shading, complex curves, etc...)