Well, I'm only a messenger, just a middle man passing on information here. But the way I read it, that means 50% of all IBL's were removed. That's not surprising to me, given the description provided about the highly competitive nature of the market. I imagine there were lots of "unusual" backlinks to deal with.
It's a little early to panic - although I fully sympathize with the feeling.
1. Have you tried the site: operator? What results does it give?
2. Have you checked to see if your server has been hacked [webmasterworld.com]? That thread and many others are available in the Hot Topics area [webmasterworld.com], which is always pinned to the top of this forum's index page. I'd suggest a good read-through there.
3. You have several ways of communicating with Google - they are all mentioned in the Google Forum Charter [webmasterworld.com] and you may want to make use of them if you can't figure out what's going on. But do make a good faith effort to understand what might be a problem and correct that first.