You can download a trial version of Windows 8 Enterprise RTM trial (build 9200).
If you want to evaluate the final version of Windows 8, you can download a copy of Enterprise edition which includes all the features and capabilities Windows 8 has to offer.
This evaluation provides a 90-day trial of Windows 8 Enterprise edition. Both 32-bit and 64-bit versions are available as ISO images in the following languages: Chinese (Simplified), Chinese (Traditional), English, English (UK), French,
German, Italian, Japanese, Korean, Portuguese (Brazil), and Spanish. In order to use this evaluation, you must register and the product must be activated online with Microsoft-hosted activation and validation services. Microsoft does not provide technical
support for this software.
The terms are straight forward, you have 90 days to try out the product and your applications, afterwards, you must purchase a license as the trial is not extendable. Microsoft states:
Things to Know Before You Start
The evaluation edition will expire and cannot be upgraded.
To upgrade, the evaluation must be uninstalled and a non-evaluation version of Windows must be re-installed from your original installation media.
Consider running the evaluation edition in a
virtual environment or installing on a separate hard drive or partition. The will allow you to upgrade your original Windows installation to Windows 8.
During registration (required) you must login with a Microsoft account and provide your name, e-mail address and country.
You are required to activate the product online within 10 days after installing.
Once the evaluation is installed, you cannot upgrade. To revert to a previous version of Windows, you must do a clean install from your original installation media.
Activation and Usage Guidelines
Back up your files and settings before installing this evaluation and again prior to the 90-day expiration.
Upon installation, you will have 10 days to activate this evaluation online. Windows will prompt you to activate. A product key is not required for this software.
You must complete activation before August 15, 2013, to use this evaluation.
Once you activate, you have up to 90 days to use the software. You can track the amount of time you have left by referring to the "watermark" in the lower right corner of the Windows desktop.
If you fail to activate this evaluation within the 10-day grace period, or if your evaluation period expires, the desktop background will turn black, you will see a persistent desktop notification indicating that the system is not genuine, and the PC will
shut down every hour losing unsaved work.
Following the evaluation period, you will need to replace the operating system on your test computer and reinstall all your programs and data. It is not possible to upgrade the evaluation to a licensed working version of Windows 8. A clean installation
So, if you agree to these terms and are willing to try out Windows 8 for 90 days for development and evaluation purposes, you can download Windows 8 right now. But, read the fine print carefully, you will not be able to upgrade this install after the expiration
of the trial is over and will have to do a clean-install of Windows post trial.