It was announced in the US last night that Windows Server 2008 Release Candidate 0 is now available for for download

As they put it:

Windows Server 2008 RC0 is a great opportunity for customers to continue evaluating Windows Server 2008 and to take a first look at the Windows Server virtualization CTP. Through their testing and ongoing feedback, Microsoft will be in a better position to deliver a final product that customers can both use and grow from. By engaging in the test process, customers and partners are in a better position to determine how they can take advantage of the new and enhanced features to help improve their IT infrastructure.