Well, I tried uninstalling and reinstalling, and my current hypothesis is that there's a fatal problem with Dogfight on Samsung Galaxy Nexus phones -- or with the Ice Cream Sandwich OS. For some reason, my email is getting mangled as it's sent to your servers and is not registering as valid. Of course this is not true as the same email/password works perfectly on my old phone.
Zup, let me know if there are any tests you'd like me to do.