From what I read, there is no signing up. Just have a compatible SIM in the tab and you're good to go for 200 MBs/month. May be wrong, but I'm pretty sure that's how the article I saw explained it. It tempted me to get a LTE N7 too just for the free data on the rare occasion I'm away from WiFi for light browsing.
Hmm, good to know, I already am on T-Mo, looking to pickup a N7 from google themselves, but wasnt 100% sure it would be eligible, good to know I can get that plus a T-Mo sim and it should work.
T4rd would you mind linking the article your thinking about? (I have the same reason for wanting to go that way, with the exception of wanting it for GPS as well). Didnt realize it was as easy as plug/play.
After skimming it again, I don't see it mentioning having to create a T-Mobile account, but even if it does, it's a non-issue esp. if it doesn't require any billing info as Jasonx82 claims.
go into the store and ask them...it will cost you one time fee of $10, but then you have to go online and register your device with tmobile. you will then have data for life on that device, but the sim will only work on that device....it wont give data to any other tablet