A few days ago, I upgraded a Dell laptop to Ubuntu 12.04 from LubuntuLinux 11.10...the upgrade went flawlessly except for one issue--my new iPad 3rd gen wasn't mounting like it once did. Fortunately, others had figured it out (yay):
1. Unplug your iPhone or any iOS5 device from your computer, then start the terminal and install first thelibimobiledevice-utils and ifuse packages:What I like about this is that I'm able to leave my Macbook in the bag, and plug into my LubuntuLinux machine, and load new books (e.g. ePub) and documents (e.g. PDFs) into Stanza's Documents directory on the mounted Documents drive via PCMANFM (file manager).
sudo apt-get install libimobiledevice-utils ifuse
2. Connect now your device to your computer and run this command:
idevicepair unpair && idevicepair pair
3. If the operation is successful, you may get something like this as returned outputs:
~$ idevicepair unpair && idevicepair pairSUCCESS: Unpaired with device (...)SUCCESS: Paired with device (...)
4. Disconnect and reconnect your iPhone 4 and it will be mounted automatically.