From Windows Team Blog
Due to popular demand, the Windows Enterprise Trial program has been extended. This means you now have till Dec 31st, 2010 to download and evaluate the trial version.
The Enterprise trial is designed specifically for IT Professionals, so that you can test your software and hardware on a final version of the product. In addition, it provides the opportunity for you to become more familiar with the key improvements over previous versions of the Windows operating system, and experience firsthand how Windows 7 can make your PC environment more productive, secure, and manageable.
Since the trial software designed for IT Professionals interested in experiencing the Windows 7 Enterprise on behalf of their organization. We do not recommend that you install this if you are a not an IT Professional or not professionally managing corporate networks.
A few thing to be aware before you install the trial.