As above, they Did, But If you are meaning a FULL fledged viewer, where you can do everything, iPhones and iPad's simply do not have the specs to handle Second Life.
Now if you do just want to do text basied stuff, Chat IM, Bussiness transactions, Then yes, Pocket Metaverse is you thing. But if your hopeing for a full SL viewer on the Apple stuff, Not going to happen.