Well every link counts, I do not see why not, also the effect would be much better if the links are follow rather than no follow.
It will surely help you if the link has follow attribute.It also counts as a backlink with your preferred anchor text.
there is an option to "Show your signature" which is checked by default if you have a signature specified.
One tips here for those who are looking forward to build links with forums. Some forums do not show signature when you are not registered or logged in and some do not reveal their contents if you are not a member. You cannot build links with such forums as search engine spiders will not be able to crawl your links.
I have to agree that signature links is one of the fastest link building strategy especially if the forum is dofollow because all posts will get indexed quickly. Try to imagine this yourself, If you post daily and spend let's say about half an hour each day, just imagine how many links would you have accumulated in a year.
signature links are an excellent way to build backlinks. It takes time and effort but in my opinion is well worth it.
If the foum is dofollow, then you get backlink. And you get nothing if there are nofollow By the way, forum signature do bring you traffic
Every dofollow forum that you have a link from counts as a backlink. Hell, every dofollow link you have counts as a backlink.