IMHO (12/2/2011)
The easiest way to penetrate a system is to have the password. As long there are phones out there with rootkits capturing urls and keystrokes, none of our systems are truly secure.
No need to have such technical expertise. Social means, like calling users feigning that you're from IT and requesting user/pwd info is frighteningly effective.
On the flipside, it's also very effective for SAs and DBAs to have automated scanners check your logs every few minutes for errors, like, oh, I don't know, login failures. If anything, it allows me to continue putting down "DB monitoring" into my timesheet without being questioned after catching the penetration testers. 🙂
Rich