Interesting report in The Register:

It has emerged that Facebook’s war on competing services now extends beyond the manipulated Timeline and into punters’ pockets. The social network’s mobile app appears to be altering address book entries to direct messages to Facebook mail accounts. A user composing an email on his or her phone will send the missive to a Facebook inbox the recipient has probably never looked at, and as the original email address is overwritten there’s no alternative.According to reports, address books on iOS and Android devices are being updated by the Facebook app whenever there’s an entry in the address book linked to a Facebook account. In some cases it seems the @facebook.com address is being appended to the contact details, but other users are reporting that it’s being overwritten too.

With most companies one would assume that this is a bug. But with Facebook…..?