UCS iSCSI Boot From SAN
Although not on the CCIE blueprint, recently I've done a couple of UCS implementations with iSCSI SAN Boot. Both have gone fine no problem, but you do have to have your iSCSI VLAN set as native otherwise it does not work..
Now in the two I've done this for have not been a problem, although I can foresee for some clients, this could be an issue (especially if the network teams have different standards etc to the server teams).
One way round this would be to use LAN pin groups and associating the pin group to an 'iSCSI Boot' vNIC template, and ensuring the correct config on the northbound switch ports (in respect to Native VLAN) marry up with the Native VLAN set on the vNIC template.
One thing I have not yet tested, is whether you can split the native VLAN at the global level in UCS when using LAN PIN groups?