A few days ago, we reported the last Google PageRank update of 2008. We're not certain if this is related, but there are a lot of interesting observations related to the PageRank update that we've seen. For once, I've noticed discussion about fewer sitelinks on some sites. In fact, I've personally been impacted by 8 to 6 sitelinks on one of my sites.
Google is also apparently giving some browser "hijacking" domains (that is, sites that don't let you hit the "back" button) a lot more visibility in the SERPs in addition to mirror sites.
We're also not sure if this is related but some people have spotted some big drops their rankings in the SERPs.
Forum discussion continues at WebmasterWorld and Google Groups
