Starting January 21, a select number of Mafia Wars players were granted access to the next expansion -- Bangkok. Want to see if you were one of the lucky few? Then go to the Bankok preview page to see if you made it in -- a pop up window will congratualate you for unlocking the new area of the game (and give you three passports to give to friends).
The Bangkok page will also have a note that says "Congratulations! You are in the Bangkok Beta," as seen in the image below.
If you didn't get an invite, get busy making sure you're ready for the expansion's official launch (coming soon) by partaking in the pre-opening loot event, where you collect a Triad Coin, Yakuza Sake and Thai Note (by playing through certain New York missions) -- all needed to get your passport to Thailand.