I read Jeff Hengesbach's blog every day, and I'm fairly sure that if you like my blog, you'll love his. He recently started it, and every post so far has been really interesting. You should check it out.
Anyway, today Jeff wrote about iSCSI SANs. If you're unfamiliar with the concept, here is a great introduction. You should also know that there are two competing standards, iSCSI (where the storage is accessed over standard ethernet) and Fibre Channel (where the storage is accessed over fiber optics cables). There's some more in-depth explanation here, but it all boils down to speed and expense.
Among the in-the-know people (AKA: not me), it seems to be a sort of common knowledge that we're going to be using iSCSI in the future, what with 10Gb ethernet being the standard just-around-the-corner. The current best-of-breed is 8Gb/s FibreChannel from IBM, but 10Gb would trump that, and the added bonus of using tried and true ethernet is very appealing to a lot of people.
Regardless of whether or not we end up with iSCSI I'm not convinced that copper will last us much longer in the grand scheme of things. I suspect that, maybe by the time 100Gb rolls around, we'll be using ethernet-over-fiber for that stuff. The theoretical bandwidth of optical is just too high to ignore in the long-term. If you want to get all sci-fi, scientists have recently began working on entirely optical versions of most basic integrated circuits.
Just a random observation to spark discussion. What do you see happening in the future of SANs?