Reports via WebmasterWorld that Microsoft released a new update for its MSN Search, Windows Live Search product over Thanksgiving weekend. Senior member, crobb305, was the first to report it, stating;
In the top 20, on a financial term I watch, I only see 4 blogspots, versus 8+ a few days ago.
In short, it looks like, to many, that Microsoft pulled many of the splog (spam blogs) from the search results.
In the past, Microsoft said they Won't Do a Search Index Update on holidays or weekends, but they are known to have broken that rule.
Forum discussion at WebmasterWorld.