Update: These instructions also apply to the RTM version of VS.
This seems to be one of the questions I am seeing most on twitter (@DougWare) so even though this information will probably be easy to find very soon as the developer center content appears, I thought I'd post what I did for those of you who just can't wait.
The problem is that I couldn't find the link to which this refers. So, to get this working follow these steps. Note that these instructions are for On Premises development and you don't strictly require a SharePoint installation if you want to develop using the new Apps model.