In the wake of the recent coup in Thailand, the new government is taking steps to suppress dissent. In addition to curfews, banning unauthorized gatherings / protests, and instructing the media not to criticize the new government, they have taken initial steps towards Internet censorship.
Facebook was blocked briefly on Wednesday by order of the Information Communications Technology Ministry. A senior ministry confirmed that the blocking was intentional, not an outage, and it had been done to slow online criticism and make it more difficult to organize and coordinate protests.
The typical pattern with censorship is for it to get stronger over time. I encourage anyone in Thailand to download the Anonymizer Universal free trial, to ensure you have a way around any of the new blocks that are likely to appear in the coming weeks.