A useful tutorial below on how to setup ESXi.  The Q1/2012 release will have it in the tutorial section.  But here is the raw text below.

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Configuring ESXi 4.x and 5.0 for Discovery and Inventory

Overview for Configuring ESXi 4.x and 5.0 for Discovery and Inventory
This tutorial will guide you through the steps required to setup ESXi 4.x and 5.0 for discovery and inventory.

You will need to complete the following steps for all ESXi hosts:

1. Download and install the latest Dell OpenManage Server Administrator (OMSA) VIB.
2. Ensure the CIM OEM Provider is enabled.
3. Configure SNMP traps.

Note: To ensure proper device classification and inventory, make sure to create a unique include range with the WS-Man protocol enabled and the SNMP protocol disabled for discovering ESXi servers.

You will need to download and install the latest version of the vSphere CLI to complete one or more of the steps in this guide. This can be downloaded from http://www.vmware.com

Download the Dell OMSA VIB for ESXi
The Dell OMSA VIB is the installation package for Dell OpenManage Server Administrator (OMSA) in ESXi. OMSA provides the interface to manage the inventory and generate related SNMP traps from the ESXi hosts.

1. Go to support.dell.com and click ‘Drivers and Downloads’.
2. Enter your Service Tag or product model.
3. Select the ESXi version as the operating system, and then click ‘Systems Management’.
4. Click ‘OpenManage Offline Bundle and VIB for ESXi’ to download and install OpenManage Server Administrator.

NOTE: For ESXi 5.0, OMSA VIB 6.5 A02 or greater is required.

For full documentation on using Dell OMSA with ESXi, go to:
http://support.dell.com/support/systemsinfo/documentation.aspx
Then navigate to: Software | Virtualization Solutions | VMware Software

Install the Dell OMSA VIB for ESXi
Using the vSphere CLI, install the Dell OMSA VIB using the appropriate command depending on the version of ESXi.
For ESXi 4.x:
vihostupdate.pl --server --username root --password -i -b
For ESXi 5.0:
esxcli --server software vib install -d

Ensure the CIM OEM Provider is Enabled
The CIM OEM provider allows the Server Administrator Web Server to communicate with the ESXi system, which is necessary for management of the device.

Since CIM OEM providers are disabled by default on some ESXi versions, you should ensure this is enabled.

To enable CIM OEM providers on the ESXi system using vSphere Client:
1. Log on to the ESXi host system using vSphere Client.
2. Click the ‘Configuration’ tab.
3. Under the ‘Software’ section on the left side, click ‘Advanced Settings’.
4. In the ‘Advanced Settings’ dialog box, click UserVars on the left pane.
5. Change the value of the ‘CIMOEMProvidersEnabled’ or ‘CIMoemProviderEnabled’ field to 1.
6. Click 'OK'.
7. For the changes to take effect without restarting the system, use the ‘Restart Management Agents’ option in the Direct Console User Interface (DCUI) on the local console of the ESXi system.
If the changes are not effective and if you cannot connect to the VMware ESXi host using Server Administrator, restart the VMware ESXi host system.

Configuring SNMP Traps for ESX/ESXi 4.x and 5.0
To generate virtual machine and environmental traps from ESX/ESXi hosts, you must configure and enable the embedded SNMP agent.

Note: Make sure the SNMP protocol is open in the ESX firewall.

To enable the embedded SNMP Agent and configure SNMP traps using the vSphere CLI:
1. Run this command to see if SNMP is enabled:
vicfg-snmp --show
2. Specify the communities and trap targets with this command:
vicfg-snmp.pl --server --username --password -t @ /
For example:
vicfg-snmp.pl --server host.dell.com --username root --password password -t target.dell.com@162/public
Note: In ESX 4.x, you may need to use the -c flag.

3. To enable the SNMP service, run this command:
vicfg-snmp.pl --server --username --password --enable
4. To verify the SNMP settings, run this command:
vicfg-snmp.pl --server --username --password --show
5. After you have discovered the ESX/ESXi host, you can send a test trap to verify that the agent is configured correctly with this command:
vicfg-snmp.pl --server --username --password --test
Information referenced from VMware KB article 1008065.