OM(F'in)G. I had an iPhone 3G that I outgrew. So I got an iPhone 4. But since the authenticator was on the 3G and ...
1) I have 5 seperate B.Net accounts so I can log all in on one code
2) I have the authenticator from the 3G locked to the accounts
3) If I put on a new authenticator I have to only use it on one account
4) I can't use my 3G (no cell service on it), I leave it at home and can't log in (no code) at work or out on the road
Now I can (just did) make my 4's authenticator sync (use serial and restore code) to my 3G's, I can use it at work, out on the road and even if my 3G crashes, I have a backup. So at end, I can still log into all accounts at once and have a way to get a code at work. /bow to Blizzard.