I would say there are two classes of customers who are going to be interested in iSCSI. The first is small to medium-sized businesses or new businesses that have no existing Fibre Channel infrastructure. People who are ready to break away from direct-attached storage need clustered storage for clusters or high-performance computing. In those cases, they may not be in the mind set to deploy a full Fibre Channel infrastructure.
Another area where people would be considering iSCSI -- even if they already have a Fibre Channel deployment -- would be smaller, cheaper development environments or people who need more speed in terms of deployment. A lot of my customers who use iSCSI report it is easier and faster to connect a server to storage from scratch than with Fibre Channel. Not having to pull cables, set up zoning that could be sensitive to other enterprise applications goes a long way. "Click, click, click and it is done" are the terms I hear.
Listen to the iSCSI vs Fibre Channel podcast here.