I would contact them at the below URL if it surpasses 28 days... https://www.google.com/adsense/support/bin/request.py
about three days it will be get approved / or not. if not you can pm me and i can check you blog why you didnot get approved
For some people it might get over 3 months to hear a reply. Try contacting them after a month from applying. Peace,
I was approved within a few hours when I joined, because of that I presumed the approval was automated. Judging by the responses in here I guess it's not the case. I must have been lucky.