Depending on your budget it might be worth looking at the SUN SANS! :-) I will be purchasing one of these to run our virtual machines. we have seen it tested and tried and it works with no problems at all! it would be better if you can get 15k disks but the 10k disks do work very well! :)
Sun Storage 7110 Unified Storage System - Overview
And even better if you get it on the Match and Grant! :D 2 SAN's! once for redundancy
Drop CutterProject an email or send kmount or linescanner a PM and i am sure they will be able to give you some advice! and prices :D
Cutter - a better way to deliver computing
If your on a budget you can make your own iSCSI san using linux or solaris. Lots of guides out there and will only take you an hour or two for the setup. Performance wise its no different to big name vendors (havent tested on installations over 35vms + cifs).
You wont get the pretty GUI but you can easily add all the features like High availability, cifs and nfs with a few commands (once again from a long list of guides and howtos). No licencing costs and you dont get locked into vendor specific equipment.