This is a great question. The answer is simple: a company that announces compatibility with an unfinished standard is simply announcing their intention of supporting the technology in some fashion. They will do what they have to, even if it means they will have to develop engineering band-aids to their products. Most likely they have an idea how to make the new standard "look like" their current technology through internal programming interfaces. Also, saying that a new standard will be supported does not necessarily mean that it will inter-operate with current technology. I know that seems insane, but sometimes that's how it turns out.
For instance, iSCSI traffic certainly should flow through Fibre Channel networks as iSCSI transported by TCP in FC/IP frames. Does that make it interoperable with FC storage on FC SANs? It depends on how you define "interoperability". I'd say no, but at least it could use the same switch. Would you really want iSCSI to travel over FC instead of Gigabit Ethernet? Somebody else can answer that.
Other than the example given above, I don't believe FC and iSCSI are going to be compatible for several years, if ever.
With all due respect to Brocade, which I think has executed better than any other Fibre Channel company, their announcement strikes me as an attempt to stall or freeze the market. They need to say something about iSCSI, but they need to do it in a way that doesn't discourage their bread and butter Fibre Channel customers. Brocade's discussion of iSCSI indicates they recognize that the introduction of iSCSI could be a serious event in the development of storage networking. What their real plans are for iSCSI is anybody's guess.
This was first published in April 2001