Bing search updates typically are hard to spot because the forums don't typically light up with SEOs going crazy about it. Why? Because Google dominates the search referrer traffic for most sites and industries.
That being said, there is a single post at WebmasterWorld that has one webmaster claiming there was a recent update. He said:
Yesterday my site dropped from page 1 - where it has been for years - to page 8 in Bing results for main money search term.
This had already happened on Google with Penguin.
Is this some sort of Penguin equivalent?
Now, I doubt this is a Bing Penguin update but I did check my analytics for search referrer traffic, while most my sites barely get much from Bing, this site did see a spike and then decline around this time.
Did you notice a Bing update in the past day or so?
Forum discussion at WebmasterWorld.