Check .NET Version with Inno Setup now includes a test for the new .NET Framework 4.5. That test was somewhat complicated since version 4.5 is an in-place update for 4.0 that reuses the exact same registry keys and merely changes some values. The check I used is the one suggested by How to: Determine Which .NET Framework Versions Are Installed.
Note: I tested that the script works as before on .NET 4.0, but I did not test on .NET 4.5 since I only briefly installed that version to check out Visual Studio 2012. I did have a look at the 4.5 registry keys to make sure they match the MSDN description, so I’m reasonably sure the new test should work. Let me know if it doesn’t!