It seems that Larry McVoy is up to his old strong-arm tactics again, forcing another free software developer to stop his work.
I find this highly distasteful, of questionable legality, and more than a little worrying for my own future as my employer uses BitKeeper. (Luckily for me, it's a big company and I've been careful to never use it myself.)
Of course it's not too surprising as this is probably the most effective method they have to protect themselves against competition. As tridge discovered, BitKeeper is little more than a layer on top of the ancient SCCS storage format. It's not that it isn't a nice piece of software with some good GUIs, but I seriously doubt they could patent their technology.