No it's not a joke, or the latest pirate version, Microsoft has released the Enterprise Edition of Windows 8 primarily for developers to experiment with.
Microsoft has posted ISOs for the 32 bit and 64 bit versions of the latest Windows 8 Enterprise Edition build on its MSDN Evaluation Center webpage and there are no restrictions on who downloads it.
As with everything there's nearly always a catch and the catch in this case is that it's limited to 90 days of full functionality. This still gives plenty of time though for those that are curious to see how it behaves and are interested in testing it.
The ISOs are available here for those that wish to experiment.
