A while back, on a thread discussing canned meat, there was some debate over canning techniques. Casaubon's Book has a couple of posts on the subject that I thought were interesting and informative:

http://scienceblogs.com/casaubonsbook/2010/05/water_bath_canning_101.php

http://scienceblogs.com/casaubonsbook/2010/05/pressure_canning_101.php