[rsynnott]

http://developer.apple.com/library/ios/#featuredarticles/Ext...

See also Core Bluetooth (though that's somewhat different, being for Bluetooth 4LE devices).

[needle0]

http://developer.apple.com/library/ios/qa/qa1657/_index.html

According to this page the external accessory framework can only be used if the accessory developer is participating in the MFi program. I couldn't find any "Made for iPad" logos on OnLive's page.