I recommend Counter Hack: A Step-by-Step Guide to Computer Attacks and Effective Defenses by Ed Skoudis as well. I think that besides subscribing to the mailing lists and attending conferences, someone interested in InfoSex should get a few good books on the subjects and start reading. Then, go on e-bay or dumpster dive or do whatever it takes to get your hands on a few old computers. Set up a honeynet on a dsl or cable connection in your basement and log everything. Try things out. Pore over the logs. Watch people attack you, see what they do. Maybe get some friends to try to break in to your honeynet. Learning about InfoSec is like learning about anything: read lots, talk to others interested in the same thing, and get your hands dirty.

If you really want to get into how software can be compromised, start looking to learn about secure coding practices and learn how to audit code. If you want a job but have no formal training, being a recognized code auditor whose patches have been incorporated into open-source programs is a good way to get a positive reputation.