Below is from the manual on WOL for guests. For the host if the NIC / MB support it then you'll be fine to use it with ESXi. Take a look at this KB article - http://kb.vmware.com/kb/1003373
Manage Power Options for the Guest Operating System
Power management options let you specify how the virtual machine responds when the guest operating system is placed on standby.
These options are not available on every guest operating system. Wake on LAN support is offered only on Windows guest operating systems and is not available on Vlance NICs, or when a Flexible NIC is operating in Vlance mode (that is, the current VMware Tools are not installed on the guest operating system).
The Guest Power Management option on the Virtual Machine Properties dialog box Options tab lets you specify how the virtual machine responds when the guest operating system is placed on standby.
To change the power option for a virtual machine, the virtual machine must be powered off.
Required privilege: Settings
1 If necessary, display the Virtual Machine Properties dialog box.
2 Click the Options tab and in the options list, select Power Management.
3 Under Guest Power Management, select either Suspend the Virtual Machine or Put the guest OS into standby mode and leave the virtual machine powered on.
4 If you leave the virtual machine on, you can also select Wake on LAN for virtual machine trafficand select the check boxes for those virtual NICs that should trigger it.
Wake on LAN is supported only for Windows guest operating systems. Not all virtual NIC types are compatible with Wake on LAN. Incompatible NICs appear in the list, but cannot be selected.
5 Click OK.