>Facebook says that it didn't mean to upload these contacts

How can you not mean to? It's one thing to say that, were it something tangible, like paper, "Sorry, mate. These pages snuck in with the others. Sorry about that. We'll pull it out. No worries."

Pulling contacts and uploading them is not a passive action but takes active action.

>and is now in the process of deleting them.

So, the question must then be asked: How do they differentiate the sources of contacts associated with an account, unless they're logging that, as well? If they're not logging that, then how are they, presumably, deleting those contacts?

Are we taking bets on Facebook being in the news again, in a months' or so time, for being found to not have deleted them? :)