Yes, SANscreen is very cool. It can do a lot more than determine firmware versions !
It is, however, an expensive enterprise product. Most clients do not have SANscreen.
The HUK has 'sanlun' which may give firmware versions.
I'd rather look at the drivers in ESX with hardware provider tools.
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff
ekashp@kashpureff.org
Fastlane NetApp Instructor and Independent Consultant
http://www.fastlaneus.com/ http://www.linkedin.com/in/eugenekashpureff
(P.S. I appreciate points for helpful or correct answers.)