BitKeeper

Projects moving away from BK
- Xen switched to mercurial

- Xaraya switched to monotone

- Linux switched to git

Linux use
"It is used by some major projects such as the Linux kernel..."

I could have sworn I heard a big fuss about BK pulling the plug in its involvement with Linux. Hence, Linus commenced writing git as a BK replacement for the Linux kernel.

Not always free for non-commercial use ...
Straight from the license (type bk help bkl) (but *not*
found on their website -- there the license is quite
different!) for free use:

(d) Notwithstanding any other terms in this License, this
License is not available to You if You and/or your
employer develop, produce, sell, and/or resell a
product which contains substantially similar capabil-
ities of the BitKeeper Software, or, in the reason-
able opinion of BitMover, competes with the BitKeeper
Software.

So, if you work at a software reseller/software store or
something, you currently (IANAL) CANNOT use this
very useful product for free -- not even for your own
private GPL development of anything. (If your employer
suddenly carries a new product ... you might be breaching
the license.)

Note that developing a revision control system under the
GPL is explicitely not allowed, both by the words of the
license and by the meaning, see
marc.theaimsgroup.com/...

You might get a waiver from Larry McVoy, if you are a
Linux Kernel Developer.

This information is partially based on the HUGE(!!) thread
in the Linux Kernel ML, archived e.g. at
www.uwsg.indiana.edu/h...