I found my answer in the following message in another discussion..
Well it depends on what you are trying to do.
What happens is that the SAN will "see" each vm (i.e.each vm will have a WWN you can set in their properties). It's not true the other way around though (i.e. the vm will (not) see the SAN).
The vm will only and always see a SCSI virtual adapter (not a FC virtual HBA) but your SCSI virtual adapter will be "marked" to expose a virtual WWN (this makes your SAN people happy but this doesn't necessarily make you (the server guy) happier than before). I haven't read the documentation yet and haven't played with it so far so I am just trying to remember what I have seen / heard in the last few months.
While I can't claim to be an expert on backup ... I doubt VCB will ever be supported within a VM (at least just because of this new technology). And certainly this won't change the overall VMware strategy that could be summarized in "keep away physical tapes from the ESX hosts / vm's".
NPIV support on VMware 3.5 is really meant to make the SAN admin happier. This doesn't necessarily mean it's a good thing (in my opinion at least): http://it20.info/blogs/main/archive/2007/03/11/4.aspx