I'm a couple of months late for mandatory ISBN-13 support, but I've uploaded Business::ISBN-2.00_01 so people who depend on the module can look at the new interface and make comments on it. It supports ISBN-13 seamlessy. Most of the internals are completely new: this was my second-ever module, and I did a lot of dumb things back then.
Interface changes (all open for discussion and improvement):
This isn't ready for production. It's pretty good, but don't blindly replace what you have now. Give it a try, and if you run into a problem let me know.