Some of you already know about the official Microsoft VHD Download Page; where you can get the VHD file of a pre-builded virtual machine with an special configuration, like Exchange Server 2007, Windows 2008 Server Core, etc. All of them of course are trial versions (including the operating system).

The latest relase was made in late December, Intelligent Application Gateway 2007 SP2 with Applications Optimizer. You can download it from here.

IAG 2007 SP2 Overview

Intelligent Application Gateway (IAG) is a remote access gateway that boosts productivity by giving mobile and remote workers, partners and customers easy, flexible and secure access to virtually any application from a broad range of devices and locations.
IAG enables IT administrators to truly enforce compliance and address virtually any remote access scenario by providing easy to configure, built-in, policies that address common applications and user environments.
IAG SP2 delivers a range of new, important enhancements for customers:
1. Runs as a virtual machine on Hyper-V for low TCO, flexible/secure deployment and simple disaster recovery.
2. Interoperability for non-Windows environments with support for Firefox, Linux and Mac.
3. New application support for Microsoft Dynamics CRM and OCS Web client.

Looking around and reading some blogs, I found also a very useful post related to this Microsoft Site: The links of every VHD available to this date, including several other interesting tools and links.

http://blog.windowsvirtualization.com/downloads

Also I highly recommend you to visit the main blog where I found those links, it has always the latest news on the Virtualization World.

http://blog.windowsvirtualization.com/

Cheers!