I thought it was BS in the beginning, but I've heard from a lot of fight fans and fighters themselves that this actually happened.
Apparently they had a sparring session and Kimbo got laid out and never returned back to train. Now this isn't really much to bug about considering you shouldn't let it all out during sparring sessions. But with the abundance of Kimbo fans (who I see on a regular basis), this has to be a blow to them.
Here's the interview from some woman about the situation as well as stuff about Fedor & Couture.
Also, the funniest thing she said was when I asked her opinion on Kimbo, she said at first she was a bit skeptical, but he came in one day to their gym in Vega and showed he had a very tough heart and trained hard. Also, him and Forrest sparred and he was KO'd by Forrest and he never came back again!
Kimbo Gets KO'd/ Fedor vs Couture info
On a funnier note though, check Kimbo here in: What Would Kimbo Do pt 3