Gah, that's lame... They're severely in need of making consolidated rollups. Kind-of rediculous to have like 8 kb files for each .net version
There is a consolidated updated coming shortly, supposedly, it's called Net Framework 4.5.1 . Net Framework 4.5.1 is included with Windows 8.1 I believe, so it probably won't be too long before it is made available. The preview for Net Framework 4.5.1 is available for Windows 8, so not sure whether they did this just for the purpose of the preview, or whether the final will be available on Windows 8 as well.
There is a MSU for Windows 8 RTM for those who are not going to be upgrading to blue, but still want the upgraded framework
I found these updates for Windows 8 (I didn't download the x86 versions). Not sure of the applicability of them, I don't have time currently to check them: I do believe however that there are even more updates available.