In the position http://www.littlegolem.net/jsp/game/game.jsp?gid=1553472&nmove=17 I was presented with the option of castling kingside in that position, even though my king would have passed through an attacked square. I don't know if the rules of 960 deal with that, but it seems wrong.
Also, since I know I'm far from the first to forget how to put positions directly into forum posts, I wish the instructions were in the FAQ.
As to putting board positions into messages, the instructions are at the bottom of the page (See "How to include game board ?" just below the "Send message" button).
It looks like this bug is still lurking, as kingside castling is available for me in this position despite my opponent having "prevented" it last move.