It came to my attention yesterday, that drug tests are being administered, randomly, to people going into Thailand, from Cambodia, by land.
Apparently, from a later update, the setup, apparently, was a portable one (tents and portable tables). So, if you have drugs in your system, and are planning to go (by land) from Cambodia to Thailand, you have been warned.
Oh, the penalties, from what I understand, are around 10,000 THB (~$300 USD). If the "guilty" party does not pay up, they are threatened with a visit (READ: stay) to the local police station.