Hi
With the M81KR (VIC) adapter you could create multiple vNICs and assign it to different vSwitches/uplink port profiles etc to provide segmentation.
Going out of the UCS system, you could use pinning (as long as your upstream is not a disjoint Layer 2 in EHM) to deterministically route traffic.
When one looks at DMZ isolation etc, a lot of it comes depends on the environment one is looking at.
Nexus 1000v has a guide published at http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9902/dmz_virtualization_vsphere4_nexus1000V.pdf (not UCS specific) on hot to achieve this using diff portgroups (VLANs essentially) /uplink port profiles/ACLs/PVLANs etc and you could apply it to a UCS environment with the M81KR.
The various vNICs presented to the hypervisor or bare metal OS are distinct PCI entities but as you correctly mentioned they are not physically segmented going out to the fabric - for example you create 4 vNICs on Side A. They all will go on the same IOM-FI link as in UCS, HIF (the interfaces downwards from the IOM) and not vNIC to FI link pinning is followed. The full width blades (with 2 adapters) give you more choices though as the number of HIFs is more.
Hope it helps.
Thanks
--Manish