I think we might be at cross purposes here, or maybe I wasn't clear enough in my response Marcus, sorry. I do agree with the fact that you can gain value and no penalties from forum links when they are used in a natural manner - for instance contributing/adding value to a thread.
I also have no evidence and wasn't suggesting that any exists in regard to contributing within a high quality forum discussion could lead to a negative impact on traffic. I note your inclusion of "high quality", which again would point to the fact that your activities were natural and adding value to the discussion, thus creating decent content, something that would never be penalised in the eyes of the search engines! Here's to a better web.
I was more referring to the original question that was posed, and it would appear that the poster is trying to gain links from multiple forums via comments posted - "Ive been try to get my links to my site in forums". They then go on to ask for techniques that can get links into forum, both of which to me suggested that they are commenting for the sake of links - which I am sure we would both agree is a low quality, dubious practice.
What I think we need is more information on Hardleys strategy here and what the intent behind it is...
You are looking at it from a seasoned professional that is using this tactic in a sensible and safe manner, which will have a positive effect in terms of referral traffic.
I was looking at it from the point of view that this could be a quick and "easy" way to increase links to your website.
One last thing is that I don't think anyone was suggesting that you should be scared of contributing to a discussion in a meaningful way - a link would again be natural in this case.
In this sort of situation the question would then be best put to the forum on which you are posting and not on here...