Coinciding with the Google pagerank update another update seemed to be taking place silently. But contrary to the PR update It was a bit disturbing for professional SEOs and webmasters all around the globe. I noticed this when I was checking links for one of my sites in Google Webmaster tool (GWT) and found that the number of links has dropped from 91,000+ to just 30,547. Later I found that GWT was showing 50 to 70% less links for100+ sites. I was shocked and felt melancholic to see it as I did not use any disavow link feature provided by Google. Several thoughts came running across my mind (Of course most of were negative). A few of them were:
1) I thought Google might have flagged and discounted low quality links to my site. If this would have happened, I feared my ranking might have dropped too. But fortunately, my rankings were intact. I checked my GWT mailbox, too dreading a unnatural link warning but did not find any such kind of mail.
2) Second thought was that Google might have discounted no-follow links or old links. This hypothesis is still to pass through the litmus test.
3) Bug: Within my hearts, I am more than sure that this is a bug or a software glitch but waiting for some words from official sources of Google.
You can participate and report your dop in link numbers on Google Webmaster thread here.