Google rolled out a new design across many of their services as part of the Google+ launch. The new look presents a sleeker, simplified Google that puts the emphasis on your data and not on the interface. Part of the design’s success are the new buttons.
Great UIs tend to have simple, obvious buttons that are standard across the entire application. Pixify has created Google+ Buttons in CSS that you can apply to your app’s UI. You can also check out Use Apple OS X Lion to Improve Your UI.
Buttons | CC License