I have to disagree with Joe. While I am not the biggest supporter of VMs on SQL (especially the potential nightmare live migrations can have on a very active server), Microsoft does in fact support VMWare on certain setups. VMWare is a partner in their Server Virtualization Validation Program (SVVP) which Microsoft supports officially under approved setups.

Microsoft server software and supported virtualization environments[/url]

Welcome to the Windows Server Virtualization Validation Program