I had also received the same message in December and responded in the App Review area for clarification. About two weeks after doing so come January, I was contacted by phone to clarify about how the logic of a feature in my app works. I explained how and then was informed that either my app will be approved, or I will be contacted again to clarify more, or I will receive a message in the Resolution Center explaining what was rejected (but more specifically, I assume). It's been over 30 days now since that conversation and I can only assume it's still being reviewed...

I've been waiting a long time too; It's been over 30 days now.