Even when I did manage to connect my Google Nexus to Ubuntu, I think it would be great to have mtp support right from the start.
Yep, here's the fix you're looking for:
This is fixed in 13.04.
As of Jan 28th
Upgrade Gvfs in Ubuntu 12.10 and 12.04 to get Android 4.0 support for devices which don't support USB Mass Storage interface
Add the PPA to your system
sudo ppa-purge ppa:webupd8team/gvfs-libmtp
sudo add-apt-repository ppa:langdalepl/gvfs-mtp
sudo apt-get update
Then, launch Software Updater (previously known as Update Manager) and install the available updates.
Once everything has been updated successfully, restart your computer, unlock your Android device, connect it via USB and it should show up in your file manager.
Please refer to What are PPAs and how do I use them? if you have questions about anything related to a Personal Package Archives (PPA) and refer to the source on OMG Ubuntu (it has some comments worth reading).
