George Crump of Storage Switzerland has written an excellent article titled NFS Saved By VMware? and posted at InformationWeek's Storage Blog. In about 600 words, George describes numerous advantages as to why NFS will become the dominant storage protocol for VMware environments. The post is short and sweet and definitely worth reading.
We have seen plenty of cases of the rise of NFS in virtual environments. Recently Beth Pariseau profiled a company making the switch from iSCSI, see AutoTrader plans VMware move from iSCSI to NFS.
Personally, I think there are bigger things here than just protocols such as who owns the file system and where does it reside. We'll see how that plays out.