While trying to install the visual studio 2012 ultimate trial on Windows 8 Release Preview I got the following error message
The .Net Framework instal
That isn't supported and isn't going to work. Both VS and Windows were evolving, and only a few very specific combinations of OS and IDE worked together. Since both are now RTM this should no longer be an issue, and MS are certainly not going to go out of their way to make these throwaway test platforms ensure compatibility.
If you are an MSDN or technet subscriber you should be able to download a Win8 RTM image for development purposes (testing, validation, etc). Otherwise you'll have to purchase and install Windows 8 retail, or install VS2012 on your existing OS (Windows 7, presumably). Likewise, VS 2012 RTM is available from MSDN. Note that VS2012 only supports "Modern UI" development (or whatever it is called this week) on Windows 8 (regular .NET framework development is supported both on Windows 7 and Windows 8).