I just read the GPL FAQ in its entirety and talked with some GPL gurus. Technically, the consent to re-liscense was already given through the "either version 2 of the License, or (at your option) any later version." clause in the pre-amble of every file. As for the translation files, they don't have a pre-amble, so they are assumed to have the same liscense as the rest of the project. Since every file with a pre-amble says that all changes can be reliscended, under clause 9 of the gpl 2 (which although optional, we have used), we can re-liscense the translation files. Same goes for the graphics.
However, in order to avoid this in the future, we should have a govorning "file" that designates all files without a pre-amble be subject to the terms of this pre-amble, such that we could reliscense to gpl 4 in 20 years without having to backtrack to today. This will avoid all the legal mumbo-jumbo and the several hours i went discussing with people about the non-preambled files.
The only persons permission who is actually needed is Kyle, as he has to be willing to host us with GPL v3. I can't remember but if Savannah hosts the source code itself that even thats a moot point, savannah themselves good re-liscense our project under GPL v3 without us :)
As long as contributors are willing to continue to contribute in GPL v3 then the switch will do the project no harm, and since no one, yet, has said no, thats a strong pattern that no one will. I very highly doubt anyone would actually care about a switch between GPL versions. If we did something like go to creative commons, or public domain thats a whole other story, I would not like my code to be in public domain, for example.