VMware recently announced that ESX/ESXi 2.5 Update 4 is available for download. Here is a brief summary of the features available with this release:

This new release of ESX/ESXi 3.5 Update 4 comes with the following enhancements:
<ul>
	<li> Enablement for platforms mounting the Intel Xeon 5500 Nehalem-EP processors family</li>
	<li> Experimental support for PXE boot with ESXi installable</li>
	<li> Newly supported guest Operating Systems:</li>
</ul>
<ol>
	<li>SUSE Linux Enterprise Server 11 (32-bit and 64-bit).</li>
	<li>SUSE Linux Enterprise Desktop 11 (32-bit and 64-bit).</li>
	<li>Ubuntu 8.10 Desktop Edition and Server Edition (32-bit and 64-bit)</li>
	<li> Windows Preinstallation Environment 2.0 (32-bit and 64-bit)</li>
</ol>
<ul>
	<li> Expanded Support for Enhanced vmxnet Adapter – Update 4 includes an updated version of the VMXNET driver (VMXNET enhanced) for the following guest OS's:</li>
</ul>
<ol>
	<li> Microsoft Windows Server 2003, Standard (32-bit)</li>
	<li>Microsoft Windows Server 2003, Standard (64-bit)</li>
	<li>Microsoft Windows Server 2003, Web</li>
	<li>Microsoft Windows Small Business Server 2003</li>
	<li>Microsoft Windows XP Professional (32-bit)</li>
</ol>
<ul>
	<li>QLogic Fibre Channel Adapter Driver Update — The driver and firmware for the QLogic fibre channel adapters have been updated to version 7.08-vm66 and 4.04.06 respectively. This release provides interoperability fixes for QLogic Management Tools for FC Adapters and enhanced NPIV support.</li>
	<li> Emulex Fibre Channel Adapter Driver Update — The driver for Emulex Fibre Channel Adapters has been upgraded to version 7.4.0.40. This release provides support for the HBAnyware 4.0 Emulex management suite.</li>
	<li>LSI megaraid_sas and mptscsi Storage Controller Driver Update — The drivers for LSI megaraid_sas and mptscsi storage controllers have been updated to version 3.19vmw and 2.6.48.18 vmw respectively. The upgrade improves performance and enhance event handling capabilities for these two drivers.</li>
</ul>
Note: Virtual Center should be upgraded to version 2.5 Update 4 and VMware Tools should be upgraded on the VMs to take full advantage of the new feature set of ESX 3.5 Update 4.