If you still believe that bitmap indexes are only useful in the columns with low cardinality. I think it is time to read the following blogs from Richard Foote. I think I need to rethink my strategy of implementing bitmap indexes in databases I am working on. However, one thing I am still believe my OLTP databases wont be happy with bitmap indexes ;-p

http://richardfoote.wordpress.com/2010/03/03/1196/
http://richardfoote.wordpress.com/2010/02/18/myth-bitmap-indexes-with-high-distinct-columns-blow-out/