Reading junk mail has changed the way I write other things, like blog posts, instant messages, and even personal emails. I'm more likely to use numbers, bullet points, and shorter paragraphs, and much more likely to close with a call to action.

Your call for papers probably shouldn't end with "Operators are standing by!" but it wouldn't hurt to establish urgency some other way. ("If your paper is ready, submit it now--although the deadline is in X weeks, we'll only be able to thoroughly review papers we get in the next Y weeks.")