A WebmasterWorld thread has new chatter about a possible Microsoft Live Search update that is taking place. The reports are very new, but also extremely significant.
Here are some quotes from some webmasters noticing the changes at Microsoft:
Has anyone noticed a large SERPs change in MSN today? For one of my main keywords I went from #1 to #41, except now it's a completely different page ranking for that term. As well most of the other competitors that were on the front page completely disappeared as well.
YES! And we went from number 60 to number 2! I'm lovin' it! Let's hope it stays like this because these are finally decent results! :)
This update has major changes as well. Most are happy, at the moment, but it does not mean that the results are more relevant. We will keep watching and let you know about any significant changes.
Forum discussion at WebmasterWorld.