Black castling long in the Sicilian When and why does Black castle long in the Sicilian? What kind of strategies should both sides adopt in such games? What kinds of games does it give rise to, i.e. positional or tactical? Which players are well known practitioners of such as Black?
Black castling long in the Sicilian is a rare thing indeed. I can think of a few reasons:


Black castling long is very rare in chess in general, only a few slow going openings (Caro-Kann, Scandinavian) feature it in general. It takes longer to prepare for long castling than for short castling, the king is less safe on c8 than on g8, white moves first so it's even riskier for black than for white.
In the Sicilian, white generally gets quick development and an attack so it should be even more dangerous.
Black has moved 1...c5, making the queenside less fit as a home for a king. 
Besides, one of the ideas of the Sicilian is to play along that c-file with a rook on c8, doesn't combine well with castling long.


So in general black only goes queenside if white has a full-force attack on the kingside and the center, and there is basically nowhere else to go.

I can think of one exception right now in the c3-Sicilian, where the queens are off the board and black can castle with check: 

[FEN ""]

1.e4 c5 2.c3 d5 3.exd5 Qxd5 4.d4 Nc6 5.Nf3 Bg4
6.Na3 e5!? 7.dxe5 Qxd1+ 8.Kxd1 O-O-O+ *


and lines similar to that.