I wouldn't be so sure about that. I believe the core database from which BDB evolved (and which was also written by Keith Bostic) is part of some pretty widely-used Unix software (SMTP servers, or DNS, or something like that).
Isn't bdb a standard component on vxworks? Android isn't the most popular embedded thing. I'm just wondering what the actual numbers are on this stuff.
BDB are used a lot on the server side, but you can't beat the consumer devices.