I spent 2 years working on the infrastructure for a large silicon valley company to make it so we could do geo located data while maintaining a good experience for the user and when I left we had never completed the project.

1. If you want seamless auth, how do you want to handle this? Do they go to eu.facebook.com and authenticate that way?

If you geo locate the user to give them the proper authentication, what happens to a US based traveler who is in the EU?

2. Shared data. Lets say an EU person (whos data isn't allowed to go to the US) is friends with a US based person. We'd like to generate a feed of data for all that person's friends. Do we now have to query a DB in the EU? Is it ok to return that data to the US?

3. What about all the rest of the infrastructure around running an application:

  * monitoring
  * logging
  * error alerts
  * backups
  * operations access controls

Its a hard problem to solve if you are starting with a clean slate. Its a harder problem to solve when you're trying to retrofit a set of technology that may not have been designed for geolocated data.

It’s not ridicolous to call it impossible to do in 30 days. In fact, my startup with 10000 users wouldn’t be able to do it in 30 days!