For vmware environments OnCommand Insight Balance (IB) (former Akorri BalancePoint) can help you see the partitions offset for vmdks on NetApp arrays (no matter iscsi, fc, or nfs to the esx server). This is also being enhanced in the follow-on 3.6 NetApp to help in other configurations. See attached sample report out IB. In this example you can see it is 3.5 instead of 4KB offset (default for windows 2003 i believe).
here is an example of the pdf report i posted - picks up the vms / vmdk partitions that are having issues ... some great enhancements hit in the next version. Has been very helpful to a bunch of NetApp customers in the past 3 months.