I presumed it was a given that Sharepoint would be able to run on Server 2008 Web Edition, however I was mistaken, and found out the hard way when the prerequisite installer wouldn’t work on a shiny new VM.
The prerequisite installer was failing immediately when trying to setup the IIS role, giving the message ‘Configuration Error’. Initially I thought this was obviously a bug because it was beta software.
After reading through the system requirements document again carefully, I found that Sharepoint requires the Application Server role, which Web Edition does not have.
Installed Server 2008 R2 Standard and it went on immediately.