2009 MAcc Applicants...UNITE! (MAcc students too)

That depends on the school that you are applying to. A lot of MS Accounting programs have rolling admissions system even with a set deadline. (I think this is especially true for public universities or programs with small class size and lots of applicants) Therefore, sometimes if you apply too close to the deadline, it can be a disadvantage.

If a school does not operate on rolling admissions system (rolling admissions = the application gets reviewed and the decision is made on first come first serve basis, rather than waiting on all the applications for the incoming class and reviewing it all after the deadline), then applying close to the deadline won't have that much effect on your chances of admissions.