If you currently develop applications which run on .Net Framework v. 3.5 and you install Visual Studio 2012 on Windows 8, you should know that BY DEFAULT, Windows 8 does not have an installed version of Microsoft.Net Framework v. 3.5.
Therefore, it will not appear in Visual Studio 2012 as depicted below:
Therefore, you will have to go into the Control Panel-->Programs and Features-->Turn Windows features on or off, and install .Net Framework v. 3.5 support.
Simultaneously, if you wish, you can also install Windows Identity Foundation 3.5 support:
If everything installs as expected, you should then be able to see all of the relevant .Net Development Frameworks as shown below: