the website is Asus Device Tracker
I'm getting the same error message on my 64gb prime. I still haven't accepted the OTA update yet. I am wanting to root for several reasons but first wanted to do my research, so I suppose if it doesn't work till I have ICS running, Then i will have to wait.
You should check out Lookout at the android market online. They have a new app seperate from there normal security app that you may be able to push to the device. It is designed to be sent to a lost or STOLEN device. Not sure if phones only or not but worth a try. I hate thiefs and wish you the best of luck.
Did you have your charge cable with it. If the battery is dead, if will need charged 1st. The thief may have no clue what the device is or where to get a cable. It then needs connected to wifi to recieve a notification. Have you filed a report with your police station? Your serial # is on the bottom of the box it came in( I'm sure you knew that but, jic).
Okay, just looked up the app. It's called 'Plan B'. Hope this helps.