I did contact professors, but mostly to make sure they were accepting students. After I emailed them, a few professors wrote back clarifying their current research projects or suggesting other potential advisors with research interests closer to mine. I don't think it helped my application at all, but rather helped me ensure that the university would be a good fit.
Regarding admissions, I don't think that emailing professors now will impact your chances of being admitted unless you're able to strike up a conversation about your shared research interests. I don't think it hurts to try, but realize that emailing professors won't hold much weight, if any, at this point in the application season.
Just curious -- where did you apply?