Nevertheless, it's annoying and there is nothing that we can do about it. If only Apple would provide the key to the developers...
Anyway, tonight, without much hope, I did the test by connecting my iPad 4 on my Ubuntu computer. Normally, you'll get two mount points: one for the photos and one for the shared documents.
It was not a complete success... Nor a complete failure. The photos mount point did work and I was able to access my photos, music and other stuff. The Documents mount point failed, sadly.
It's the first time I've seen a new iOS release work partially and to me, that's good news.
Now we have to wait a few weeks until the developers of libimobiledevice can figure out the new key and we'll be in business in no time.
Until then, you can always exchange documents using a NAS or a file sharing-app-over-wifi on your device.