Well, to be clear, the issue isn't necessarily with XboxFriends but rather a side effect of Xbox.com. Ever since Xbox.com added the messaging features, just visiting your friends list (and message list) "connects" you to Xbox Live momentarily (at least this seems to be the behavior). There's two states that I've seen because of this. One is that it will show that you were online 1+ minutes ago and the other is that it will not show any current presence information for anyone who is visiting the Xbox.com website. Not sure if they would consider this a bug or not.