Will the links in my sig and any links to my site I include at my posts here at DP improve my PR and SERPs??
They do help in their own little way, although they may not make such a profound effect as you might think that they do. Do not post your keyword here in the title of your post You will never be able to outrank DP for that term in G.
They are great for getting a new site out of the sandbox from what I hear... But I have noticed that a lot of the backlinks count as at least something, since they show up in my Google Sitemaps report. I'm sure they are better than nothing! As an example, I've had my blog feed URL the same for about a month now. I rank very highly for keywords that include words in my DigitalPoint Feed anchor text .
Not to any large extent. For one thing, any ranking power from a page is divided among all the links on that page, and I see lots of them on this one. Next, Google has figured out signature links and how to devalue them. The links can help get a page indexed more quickly, but they won't have a profound effect on ranking.
You might get some traffic; if you have a good site, they might bookmark you or stumble or digg. As for any link pop bump I would suspect not much.
I don't think they count much for PR nor SERPS. What the DP sigs probably do is make the internet bots ALOT more frequently. So if you have new content on your site it would probably find its way onto the search engines faster.
in terms of PR, you will only be benefitted it the thread itself gains any PR. more active a thread is, longer time it stays on the front page and higher PR it gets. so you get a little PR benefit that way. but most regular posts don;t end up staying on the front page and most of them don;t have any PR of their own. so if you want to get some PR benefit, what you need to do is to come up with a thread that forum members will find valuable and will keep commenting on. but PR or no PR, it certainly helps getting your site indexed as other members here say.
So the links aren't nofollow; if your page has pagerank they actually count towards increasing the pagerank of everyone who posts in the thread?
In theory sig links should help the most from threads on forums which are close in topical nature to the general subject of your site. However most topical forums I've found lately the admins have killed any ranking benefit by making all external links NOFOLLOW.