Accepted vs. published (for grad math admissions) For an applicant to a high ranking U.S. graduate program in mathematics, how much more beneficial would it be to have a (coauthored) article published rather than accepted for publication?  

(If more details are relevant, without possibly breeching anonymity, there are a few student authors and one faculty author.  The article is on a recreational mathematics topic in an expository journal.)
I don't think published versus accepted for publication matters a lot for a PhD position (or indeed any position). The date of publication is determined by the editors (I think) and not by you. If your article is accepted for publication then it is already in final form (as far as the content - which for most mathematicians is the important thing - is concerned). The difference between published and accepted for publication is, in a sense, a mere formality.