Update Downloader is an application for your computer that gets Titles from the Nintendo Update Servers, decrypts them, and saves them to a folder. It allows you to choose which version of the title to download, so you can examine earlier versions.

Please read the readme, as to prevent anyone from asking stoopid questions. The readme also contains a link to a file telling you which titles changed in the 3.4 update, so you can download all the titles affected by the update.

There is also a bash script inside for downloading all the versions of the System Menu, from 2.0 to 3.4 (U?). See System Menu Versions for a list of all versions of the System Menu.

Via Wiibrew.org