First off, the inbox be2net driver delivered from VMware is no good, make sure that you download the right driver from VMware's website ( 4.0.355.1 ). The inbox driver causes some serious problems if you use more than a single VLAN on the network end. You can install the driver using VUM, or you can use VMware Image Builder and inject the new driver into the installation media.
Now for the fun part, in order to use the 4.0.355.1 driver, you need a compatible firmware loaded on the Emulex OneConnect adapters, and 2 months after the release of vSphere 5.0, HP is still unable to provide a 'supported' firmware. The closest thing that you can find from HP is the 4.0.360.7 firmware:
Unfortunately the release notes don't paint a rosy picture for users of FCoE:
IMPORTANT: Emulex Firmware Version 4.0.360.7 enables support for HP ProLiant G7 BL servers and Virtual Connect with VMware vSphere 5.0. Support for FCOE functionality on the CNA is not included in this firmware. This firmware release does not support PXE Boot on a ProLiant server with AMD processors. This firmware release also does not support hp CloudSystem Matrix/Matrix Operating Environment. NCDE 10.45, which includes updated Emulex firmware, is targeted to be released in the mid-November timeframe to address the remaining critical customer issues such as: FCOE Failover not recovering, EDD looping or Hang, PXE not responding, slow PXE performance, PXE failures with Hypervisor, Red Screen, and Intermittent Ping loss.
On top of that, if you'd like to be able to use CIM providers from both HP, and Emulex you're out of luck as there is a problem with the HP CIM provider ( and the way they overlay libraries ) that conflicts with the Emulex CIM providers. Which leads to a pretty uncomfortable truth. It's pretty clear that VMware doesn't do any validity checking of 3rd party VIBs, it's also clear that vendors don't check their modules against any other vendors modules ( even if they're partnered ), which leaves a pretty big support gap as there is no one that you can call to get this kind of mess straightened out. So even though all of these components are on the 'compatability matrix' provided by VMware, there is still no supported way to get them all working harmoniously. I can say that VMware has been helpful at driving the conversations between the vendors, but the lack of even rudimentary testing by VMware is troubling.
HP maintains that they should have a OneConnect firmware available in a few weeks that should have support for FCoE ( 3 months after GA release of vSphere 5.0 ), but they're also maintaining that they won't construct a new VIB that doesn't do the overlay wrong until Feburary of 2012.
As a side note, it looks like HP has produced a publicly consumable depot for VMware VIBs. If you point VUM at http://vibsdepot.hp.com you should be able to have it automatically check for driver / CIM provider updates without manually checking their website, a trend that I would like to see other 3rd parties follow.