As I understand it, according to the BitKeeper license, you're not even allowed to think about writing a Source Control system while you're a paying customer of BitKeeper. This was the primary reason that the use of BitKeeper for the Linux Kernel was a pain - folks working on subversion and friends weren't allowed to use it.
In a related story, I was there when at LinuxConfAu2005, Tridge took an opportunity during a keynote to 500ish hackers to say, "I'm not a genius reverse engineer, I didn't use magic powers to write SourcePuller." And told the audience the host and port of a BK repo, and asked how he'd go about reverse engineering it. It was very well staged. The responses, '
telnet hostname portnum', '
help' and '
clone' (clone was in the help text provided by the BK serevr) were all that was required to make a very impressive quantitiy of code start streaming from the BK server over the telnet session.
It evoked quite the, "well now isn't Larry a silly boy" response from the crowd.