they've posted to their facebook page that they've submitted an update to Apple that should fix the issues.
UPDATE: Weve submitted Friendly 3.5.1 Fix to Apple. Apple has agreed to review it in priority, and is currently working on it. I will post an update as soon as the fix is available in the App Store.
The problems (startup,black screen,m.facebook...) were related to a change Facebook has made to their server, and unfortunately is affecting all versions of Friendly.
Thanks for your patience and continued support.