Host headers do work with SSL-enabled sites—With the introduction of Windows Server 2003 SP1, it became possible to use host headers for addressing SSL-enabled sites.
I’ll have to go and read about this one. I suppose this is what you find whilst RTFM.
Edit: Include MS HMC Documentation – I think this needs updating as there is no downside to host headers now. WTF!
When you create a new Web site, the specified approaches to addressing have advantages and drawbacks, as follows:
Using host headers saves money—Rather than purchasing a large block of IP addresses from ARIN, you can purchase a smaller block of addresses. You only need to use one address from this block for a whole collection of sites. Individual sites are identified by host headers — the Web server reads the header in the incoming HTTP request and directs the request to the appropriate site.
Host headers do work with SSL-enabled sites—With the introduction of Windows Server 2003 SP1, it became possible to use host headers for addressing SSL-enabled sites.