From Thai Airways website:
Thai Airways International - Australia - Royal Orchid Holidays
Updated : Wednesday, 26 November 2008
Please check traveller information and advice at www.smarttraveller.gov.au
As a result of political demonstrations at Bangkok Airport, please be informed that Bangkok Suvarnabhumi International Airport will be closed until 6pm Bangkok local time (10pm AEST).
Not sure what their source is though.