Google Noah's Ark?

Something massive is happening I think. Many of my well established sites with strong link profiles, social media accounts and great content are dipping by like 50 positions! WTF! Anyone else experiencing something along these lines?

Did you check your links in GWM?
I did, and lots of my links are gone, Google says something is wrong, but i think there is a massive update. Yesterday my #2 keyword was out of the top 50, today it is back on his established position #2. I had also some keywords on #18 and #22 (just started linkbuilding with this 2 keywords,) in one week i had them from nowhere to #18 and #22, they droped to page 4 and 5. Also something strange is that my 100% WHS page who had a pr1 has a pr2 now, and my more BHS site had a pr0 and now has a PR5, from 0 to 5 in only 3monts, and i did nothing special with this site, at the moment it is all confusing!
Regards

This is also being discussed here: www.BlackHatWorld.com/blackhat-seo/showthread.php?t=527617