tedster - 8:50 pm on Jan 24, 2012 (gmt 0)
This has rolled out for around 1% or queries. I strongly believe that Google will quietly roll it out to more and more queries in the next few weeks.
I read Google's communications a bit differently. I read that the algorithm is in effect universally, but it only makes an impact for about 1% of all queries. The exact quote is "This algorithmic change noticeably affects less than 1% of searches globally."
Panda is a much more involved algorithm, and it apparently needed to be rolled out in segments according to how long-tail the query was. But I didn't get that in the communication about this Page Layout algorithm. It could be that way - I just didn't read that in what Google actually said.