It may be that this is simply a function of the age of most of the forum participants. My impression is that most of the people posting there are grad students and postdocs, with a few people who have recently transitioned to more permanent positions. Also, people who are established in industry probably have other, more efficient means of obtaining career advice, including places like linkedin, their own network of contacts, or other more industry-specific blogs and forums.
Leaving aside the AAAS comments, as I think that issue has been sufficiently beaten, I would like to comment on the part where industry people communicate with each other. More specifically I would say that I don't think we are any better! There is no site I can go to and ask questions on the industry side either.
How do I know what I want to do next. ummm... I don't really, but I do look at succesful people and talk to them. I have had the "pleasure" of spending a large amount of time with a CEO and currently report to a very senior person at the large company. By most measures I am pretty far up the chain. BUT - I do spend an inordinate amount of time going "what am I doing?". SO - I ask. Not in a pleading kind of way, and only with people I can trust.
To flesh this out a bit, and I have absolutely NO idea on whether this works for other people or even will work for other people.
After I work with people for awhile (defined as more than just a few days - easily several weeks) I figure out which ones are bright, have made good decisions, and know the lay of the corporate landscape. You need to, very quickly, weed out the people who whine about where they are, complain about how "the man" kept them down or the organization doesn't appreciate them, or rely on "seniority" to get where they are going. I, and this fits with me, look for the people who are on board with the idea of driving the organization ahead as rapidly as possible. NOTE: They have to be realistic as to what the political landscape of a company will allow. Just being a reactionary highly driven pain in the rear will get you to irrelevant NOT to results.
So - once I know those people - I learn from them. If they do something in a meeting that doesn't fit with what I know their goals are - ask them later and alone why they did that. Tell them where you are trying to go, they may tell you something about the way to get there. Tell them what you are trying to learn. If they respect you, they will push opportunities for those things your way.
That is how I do it... BECAUSE I don't know any other way. I *wish* there was a place to ask questions. I wish that there were more people writing about it. I wish there were "instructions".
All of that said, these things may be impossible. The "instructions" most certainly are impossible as the situations are all over the place. The "board" probably wouldn't work as I don't, in general, trust people I don't know (and thus write a blog for people I don't know thinking they might care about what I say....).
SO - LinkedIn and it's ilk are useful to me for finding people and for when I was hunting for jobs. For getting career advice, I haven't found them to be too useful (and I only use LinkedIn and Plaxo)