The MSN Search bug we reported yesterday where MSN Listing Same Top Five Sites on 1st & 2nd Page Search Results seems to have been caused by an MSN update that took place the night before.
MSNdude confirmed last night that the update did indeed occur;
You guys are correct; there was an update last night. Somehow I had thought this would happen later. Apologies for giving you wrong information earlier.
In that thread, some reported similar issues to what I reported yesterday morning via DigitalPoint.
Forum discussion at WebmasterWorld.