I am currently using Project Tango in UK. I tried to use system update to upgrade to Nash release, but it shows "your system is up to date". I am sure the device is currently in Libnitz. Is Google blocking OTA out of USA?
i'm using Tango from France, and typically my Tango detects/receives each update about 1 week after the official release date, whatever the reason. (I let the device on, with internet access through Wifi, during my daily devs). I'm currently in Leibniz (1.10) waiting the latest 1.11 to be detected/downloaded. By the way, if you just get a NEW tango, the gap of software between it and latest release may be important : for instance, the latest new Tango we get last month was in January 2015 software version (i.e. a few month gap, so). Hope it helps. ;-)