Ibrar,
Can you take a look at B-Tree emulation for GIN ?
http://archives.postgresql.org/message-id/491B1888.9020903@sigaev.ruhttp://archives.postgresql.org/message-id/Pine.LNX.4.64.0811191828050.7862@sn.sai.msu.ru
Nobody has reviewed this at all.
--Josh