I was just reading over on Matt Cutts’ blog that the current Google Update is still in process and that will most likely show more flux in the search results pages for the next two weeks. Many people have been hit pretty hard with the new algo tweaks and update that Google has been rolling out. I have seen a few sites get pounded pretty hard. At this point, my guess is that they have implemented some new filters or other technology that allows them to weight incoming links based on page location, number of links with the same anchor text, surrounding text, and page theme. This is a guess of course, but it definitely looks as if transient links might be getting filtered out as well as forum signature links. It will be interesting to see, that is for sure. Good luck.