Within ESX 4 the /ui/ website has been disabled by default.

To enable the site, you will need to start the webaccess service.

service vmware-webAccess start

This will start the /ui website on your ESX host.

This service is not required by tools such as BMC Patrol, nor is it required to create web console URLs for Users and Developers to manage their VMs as these should be created through Virtualcenter URLs not direct to ESX URLs as VMotion/DRS/HA will break direct to ESX URLs.

For tools such as BMC products, you will need to allow access to the ESX host itself via AD integrated authentication or local users.  This needs to be modified in both the Users and Groups tab, as well as the Permissions tab.