Windows Server 2008 R2 is the current version of Windows Server with the next edition being expected in 2012 or 2013. When connected with a desktop user, the typical functionality we might expect to deliver which has any overlap with Windows Intune is as follows:
Identity management with Active Directory
Group Policy
Update management with Windows Software Update Services
Windows Server can deliver many other benefits to the user, including additional security management, file storage, and web serving, but these are more about services the user may use and have very little overlap with Windows Intune.
One very important difference between an on-premise based solution using a server and Windows Intune is the need to manage the server and all the tools. Windows Intune provides this functionality without you having to manage it, while Windows Server, Small Business Server, and Windows Home Server all require a server on premise.