My first analysis was the Bangkok bomb had military grade explosive (and flash), targeted at tourists to hurt Thailand's tourism industry as a whole.
Given the deepening ties between Thailand, Russia and China and their approval of a Palestinian State it was only a matter of time before the axis of evil (including CIA and MI6) would attack Thailand. I also have it on good authority that the Royal Thai Police are aware of Mossad drug trafficking through Chabad House in Bangkok.
I don't agree with all the points made in the following article but I think the Bangkok bomb was from outside forces and the only suspects are the usual ones when it comes to international threats and intimidation.
The bomb plays into whoever is in power's hands as they can crank up the need for security against their enemies. I notice the military grade explosive and flash was downgraded to 'improvised device' in the media, which tells me the people who know, don't want others to know.
Another excellent write up is over at Aangirfan