There are two threads with complaints from webmasters that Microsoft's search crawler, now named BingBot, is crawling way too heavily.
The threads are at BingForums and WebmasterWorld. Yes, the discussion is often very limited when you are watching over Bing, simply because many webmasters and SEOs devote 99% of their attention to Google.
That being said, some are claiming BingBot is acting out of control. Honestly, if it was really bad, I believe more people would be complaining. But Microsoft does have a history of crawling too fast, cloaking their bots and creating fake referrals.
Did you notice a spike in your BingBot traffic and crawling?