I work in banking and find linkedin to be extremely useful. It is a great way to map your network and also to publicise your existence to the wider banking community.
Think about it - You are the new kid on a desk, your desk knows you, your brokers know you. That's it! It's a great way to advertise yourself, almost like a CV on public display.
For students I think it's pointless, you have no reason to be on there! Use facebook and get drunk instead!
Check my blog out (accessed via my profile) for my other thoughts on finance and banking!