After this Panda & web spam update I am in a lot of fear as of where its ok to place my site. I was wondering if No-Follow Signature links could be considered as spam to Google in anyway? They are No Follow from a relevant forum. Think Google could penalize a person if they posted at this forum everyday? How many forum sigs at different forums do you think is OK? Before Google looks at it like spam?
I don't think Google will think that No-follow links are considered spams. As long as you are related to the niche of your content, I think it's perfectly safe.
locke815 is right. No-follow links won't directly hurt SEO, but they won't help SEO either. I'd be more concerned about making relevant forum posts.
No. You don't need to worry about no-follow links because google will never consider such links as spam.