The best piece of background material I've found on the topic of interoperability and why it's critical is Varian & Shapiro's "Information Rules". It even has its own website: http://www.inforules.com/, though you need to buy the paper copy, and it's well worth it.
For german readers: The translation is available under the utterly misleading title "Online zum Erfolg", 1999, Wirtschaftsverlag Langen Müller/Herbig, ISBN 3-7844-7395-4.
Hal R. Varian has further online materials on his Economics website at http://www.sims.berkeley.edu/resources/infoecon/
Matthias