The second Summer of Xbox Live Arcade title has been released today. Braid is available in all Xbox Live Regions. Here is the dashboard description:
Manipulate the flow of time. Rescue the Princess. Contemplate the world; save yourself. The full version of Braid allows you to visit all the worlds, and thus use all the time-manipulation powers. Perhaps you will find the Princess and rescue her.
As usual, a trial for the game is also available to download if you are not so sure about splashing out on the 1200 Microsoft Points tag. You can view the achievement list for Braid here.