Storage Area Networks Next Generation - The move to 4 Gps: Learn about Fibre Channel, SAN, Storage Hardware, Storage Infrastructure:

Fibre channel SANs have entered the 4 Gbps world doubling, the speed of the storage communication interface and improving overall storage performance. As the industry standard shifts to a 4 Gbps FC storage infrastructure, now is the time for organizations to start to plan the transition to this new standard.

More speed is always good - I don't think that anyone would disagree with that (at least, when talking about pulling data from, or pushing data to your SAN.) Of course, if you're planning a migration, you want to think about how to go about it. HP, rather unsurprisingly, has already put that thought in, and has some recommendations for you...