Jonathan Blow has announced that the release of Braid has been delayed to "fix some problems that came up in testing with various versions of Windows".
Blow writes, "Sorry for the delay, I know folks have been waiting a long time for the PC version and it's not so great to have to wait an extra 10 days, but it's only so that I can try to ship you guys a version that works well (which frankly is impossible in Windows, but the best I can do is make it work for most people most of the time)."
The news post suggests that the game will be released 10 days later, although gives the new date as August 10th. We can assume that he meant April 10th.
Blow has updated the story with, "This post incorrectly listed the new date as August 10th. It is April 10th."