I recently posted a vulnerability in several models of the Rockwell Automation MicroLogix product line, and noted that, per the security researcher, Eyal Udassin of C4, Rockwell had been completely cooperative with the security researcher in working out a solution to the problem.
Walt Boyes just posted this message: "Go visit www.us-cert.gov/control_systems" on Twitter. (If you're not following @waltboyes, why not? Seriously, Twitter isn't just about wasting time at work. But I digress.