Microsoft has acknowledged the screw up by Target in the US, which sent out some preordered Xbox Ones two weeks before the console's launch and said that anyone who does get one early will be unable to connect it to Xbox Live.
This is the full statement sent to Kotaku by a Microsoft spokesperson:
Due to a retail partner's system issue, a very small number of Xbox One consoles were shipped to consumers before the November 22 street date. We're pleased to see the initial response to Xbox One has been so positive, but given we are still putting the finishing touches on our games, UI and online services, as well as confidential partner and media agreements, these console units will be restricted from connecting to Xbox Live until closer to our launch date.
The Xbox One will require a 500MB, day-one firmware update to play games. A total inability to connect to Xbox Live would seem to prevent the download of that title update. We've followed up with Microsoft to ask, basically, if any of these early-shipped Xbox Ones are even usable until they're allowed into the network. If we get a reply, we'll put it here.
Update: The Microsoft spokesperson reiterated that early Xbox One users will be unable to connect to Xbox Live, but did not elaborate further.