This was covered some in the Thai Festival in Silver Spring post, but there are only 5 days left (until April 19th) to try Thai Mangosteens in the area for Thai Restaurant week.
The fruit is amazing, and free with your meal at the participating restaurants!
I read that it will be unlikely anyone can actually buy Thai Mangosteens here in the US in the near future. The fresh one's you can get in NY and LA are supposedly from Puerto Rico and go for $10 each.
It's also a rare opportunity to try other fruits imported from Thailand including Rambutans and Longans.
Details and participating restaurants: