Google may have just made a pretty big mistake that could leave several developers out in the cold. It seems that Google may have been doing some 'house-cleaning', getting rid of spam and dead apps, and inadvertently included several reputable developers in their cleanup by accident. Several developers are saying their apps have been removed from the marketplace without warning and without reason given.
There is no way to confirm yet whether these apps violated the TOS at all, but at least one of the developers was even a 'featured app' on the Market not long ago. Right now, it's just a mystery, and there's no response yet from Google in the support forums, but we will try to keep you updated when something comes to light.