There's defintiely no consensus in Thailand as to the perps. And it appears that few locals blame the Muslims.
See:
http://bangkokpost.com/News/07Jan2007_news01.php
Plus:
http://bangkokpost.com/topstories.php?id=115803
And:
http://www.nationmultimedia.com/2007/01/07/headlines/headlines_30023469.php
[FWIW, my Thai wife thinks ex-Prime Minister Chavalit is behand the whole thing -- this in spite of her rabid disgust with the Muslim terrorists in southern Thailand.]