CBSE spokesperson while taking to media on this said, "Since the number of students in class 10th opted for board examination have gone enormously down as more are opting for Continuous Comprehensive Evaluation (CCE) format, we got the results prepared before class 12th. Moreover, there is no rule written that 12th results have to come before class 10th".
In the Chennai region results of class 10th, 99.66 % students managed to qualify for the admission into class 11th where out of 1, 52,086, 64% students appeared for the board exams and rest opted for CCE from the region.
Once declared, these results can be checked on the official results site of CBSE on http://cbseresults.nic.in and on the various other results portals. Students can also register themselves on the mentioned site to get their respective results via email, when declared.
Update: As per the latest statement released by the Board, Class 12th results would be published on 28th May'2012 at 11:00 am. Read More here