Exchange Server 2010 RC is now available for download. If you feel like testing the latest release of Exchange, you can install it on your own Windows Server 2008 SP2 or Windows Server 2008 R2 machine.
There is also a pre-configured VHD available which you can run on a Windows 2008 Hyper-V server. Currently this is still only the BETA version of Exchange but an RC version of this download is expected to become available as well.
Don’t forget to read more information about the new features in Exchange 2010 if you are interested.