Almost everything in facebook is openly accessible via API if you've granted permissions to an applications to do so. We've seen services like Tweetdeck and Seesmic and Brizzly act like portals to the data.
Things get complicated with friends' data of course. Facebook has a collection of your friends phone numbers, and data access permissions and storage rights get complicated.
I used to work for a social network that wanted to let users get their own photos out of Facebook and into our network. We built a Facebook app that expressly served this purpose; users only enabled it after knowing what it would do and desiring that consequence.
A few weeks after we added this feature, Facebook told us if we kept doing this -- if we kept letting users import their own photos -- our API access would be terminated.
Things get complicated with friends' data of course. Facebook has a collection of your friends phone numbers, and data access permissions and storage rights get complicated.