Something about this bug makes me just desperately want to close it as "worksforme", but I'm speaking as a facebook user rather than a facebook developer :-)
hopefully this is a feature not a bug
For at least the last 2 hours, users haven't been able to add any applications. If you're developing for Facebook (like me!), please vote for the bug (see link). And if you work at facebook, please fix it!
it seems like this is fixed
Yep, looks like they fixed it about half an hour ago.