StackOverflow is easily, without dispute, the world's premier, foremost, [insert ultimate adjective here] programmer's forum. If I'm hiring programmers and applicants don't have a SO profile; they likely won't get hired.
Do we have any idea about where we rank in terms of other Information Security forums? What can we claim about ourselves? How do we compare to other forums?
To me, Security Stack Exchange occupies a niche that no other online resource fits, so I'm not sure whether comparison is the right activity.
When hiring, I certainly wouldn't have activity here as an essential for applicants, unlike your SO comment, however if applicants have activity here and it is positive, it will certainly count in there favour.
Paid resources such as ISF and ISACA provide some very structured materials, and there are various forums that are 'classic' discussion forums at all levels of technical specialisation, but none of those fill the same Q&A space.
Now, I am of the opinion that this means in some areas we lose out on some specialist information, where individuals may well post on a dedicated forum, but in other areas, we have leading edge information (eg the Bears and others on new vulnerabilities) and we have a very collaborative and encouraging site that does provide an element of mentoring, and a scope of questions from complete beginner to expert in a wide range of security areas - and I don't see this anywhere else.
The closest comparisons would be Reddit /r/netsec (reasonably active) and Quora Information Security (fetal). Security Stack Exchange trumps both of them for activity, and I expect for reach also.
Online security discussion tends to be more focused around blogs than forums. Twitter is probably the only single site with more infosec activity than on here, but is not a direct comparison.
In the past, the Security Focus mailing lists were the most active for online infosec discussion, but they are pretty quiet these days.
Disclaimer: all of this is from my personal experience only
