Those who are running vSphere ESX(i) and have the Cisco Nexus1000v installed might want to read this:

If your customers are on ESXi/ESX 4.0 and want to update to U1 using the vihostupdate then first they need to read this new KB:

http://kb.vmware.com/kb/1015879

From here you will see mention of a file VEM-4.0.0-update01.zip which is not on the U1 download page. One useful addition to the KB article would be to remind customers that to obtain this VEM update you need to navigate to: http://support.vmware.com/selfsupport/download/

From here select “VEM” and “4.0.0” and search. You will then see VEM-4.0.0-update01.zip. Copy this to the same folder as your ESXi patch file (ESXi-4.0.0-update01.zip) and then run:

vihostupdate --server <server> --username <uname> --password <passwd> --bundle
ESXi-4.0.0-update01.zip,VEM-4.0.0-update01.zip --bulletin
VEM400-200911014-BG,ESXi400-200911201-UG –install

Let the install run….that’s it.

C:\Program Files\VMware\VMware vSphere CLI\bin>vihostupdate.pl --server
192.168.1.1 --bundle C:\Install\U1\ESXi-4.0.0-update01.zip,
C:\Install\U1\VEM-4.0.0-update01-v100.zip --bulletin VEM400-200911014-BG,
ESXi400-200911201-UG --install
Enter username: root
Enter password: vmware
Please wait patch installation is in progress ...

The update completed successfully, but the system needs to be rebooted for the changes to be effective.

Source : http://www.yellow-bricks.com/2009/11/20/esxi-4-0-esxi-4-0-u1-update/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+YellowBricks+%28Yellow+Bricks%29