[Note: since I started writing this, I found out Bess & Co. store MARC-XML. That makes a difference, since XML in Ruby can be really, really slow]
[UPADTE It turns out they don't use MARC-XML. They use MARC-Binary just like the rest of us. Oops. ]
[UP-UPDATE Well, no, they do use MARC-XML. I'm not afraid to [...]