If you've been thinking "Well, I don't think I'll buy Programming Windows 6th edition right now for $10. I'll just wait for the next time they make the $10 offer," I recommend that you study the pricing chart on the Microsoft Press blog.
This is it. This is the last day.
Programming Windows, 6th Edition
Special Price through the End of May 2012!
For just $10, you get:
(1) the Consumer Preview ebook right now
(2) the Release Preview ebook in a couple months
(3) the final ebook in November
Programming Windows 6th Edition
Consumer Preview eBook