I decided to pre-order SimCity and I have definitely been annoyed by their server issues, but I decided to track down for myself as much info as I could about what's going on.
1) All of the servers seem to be running on Amazon EC2 (or other AWS type services). This is what gives them their different zones. Fun enough, most of the communication seems to just be a HTTP API, and they aren't doing any type of UDP streaming of data. Sadly I haven't been able to MITM the encrypted stuff yet to see what's going on with transferring of game state data.
2) While EA/Maxis's official PR lines have been pretty quiet, a few of the Maxis dev staff have been posting what they can. Here are a few links around information they have been sharing:
One of their server guys: https://twitter.com/derricks
Maxis Employees on Reddit: http://www.reddit.com/user/ryani and http://www.reddit.com/user/MaxisMC (they have been posting at least a little).
3) They are trying to gather as much feedback as possible to find out where people are having the most problems to get those issues fixed.
With this game being so reliant on their servers, they should have done a few stress test weekends, but sadly, they decided not to do that and EA's customers are now stress testing on a live setup. I'm sure engineering didn't want to do it this way, but that's how it ended up happening.