Microsoft's Major Nelson confirmed the early shipments, saying that only a "very small number" of consoles went out to gamers ahead of schedule. While Major Nelson didn't specify which vendor was responsible, it's since been revealed that Target was the one that missed the mark.
Image Source: Twitter (Moonlightswami)
Twitter user "Moonlightswami" tweeted a picture of his Xbox One console and then posted an unboxing video on YouTube showing a 17-second boot time and 500MB day-one patch. Microsoft had the video taken down for copyright concerns and further banned Moonlightswami's console from Xbox Live, but it's only a temporary ban until closer to the console's launch.
"Alright, I talked to Major Nelson and all is being resolved. He has invited me to the launch event. Details on it are classified," Moonlightswami posted to Twitter in one of several updates.