CAT 2012 is happening from 11th October 2012 with 21 days test window. September MAT is being conducted on 2nd September 2012. IIFT is being conducted on 25th November and NMAT is also being conducted from 11th October with 5 weeks test window.
Other notifications of major exams to follow are XAT, SNAP & CMAT. Keep watching this space to be updated on dates.
Serious MBA aspirants like you have already on 2nd Revision and are practicing on MOCK TESTS which will give you a cutting edge to compete in exams with success.