As soon as the Galaxy Nexus hit the stores across Europe, fans began to notice that there was no support for USB mass storage and began to question how such a feature could be left out of the much hyped Ice Cream Sandwich. Well, Ice Cream Sandwich is there to prove you wrong, as the latest version of Android does in fact support this feature.
However, the issue in making use of the feature lies in the fact that the Nexus does not have a microSD card slot. The USB mass storage device requires direct access to the phone. When the device blocks this storage method, the PC will be blocked as well.
Android have confirmed that Google are working on fixing this issue and that there is no doubt that the Galaxy Nexus will eventually be able to support and utilise USB mass storage.
It has also been confirmed that all phones with removable SD cards will be able to make use of the USB mass storage once they receive the Ice Cream Sandwich upgrade. In the meantime, the Galaxy Nexus is already available in the UK market, though supplies are incredibly limited.
We are still awaiting confirmation of a release date in the US
Source: Galaxy Nexus to Receive Mass Storage Support | | The Red 99The Red 99