Microsoft’s really come a long way in how they market their products. Exchange 2003 offered a test-drive version of Outlook Web Access, and Exchange 2007 has expanded on that theme by offering test-drive and downloadable versions. OCS 2007 has upped the ante by offering some very cool virtual labs that you can use to play around with the OCS software. You can do a variety of things, including setting up UM on an Exchange 2007 server, setting up conferencing, and deploying Communicator 2007. My personal preference is usually to download the bits and set up my own VMs, but this is a nifty time-saving way to play with OCS with minimal investment of time on your part.