It depends on what sort of advanced optics the drone has. Given the lawsuits from celebrities over tabloid candid shots, an IR camera pointed at your bedroom at Oh Dark Thirty could give the court pause to reconsider.
Again, UAVs aren't really bringing anything new to the table in that regard. The courts have already ruled on the use of sensors outside the range of human senses (such as near-IR and thermal imagers) without a warrant. There's no reason why existing statues and precedent can't be applied to the sensors on a UAV.
As for the Attorney General's statement regarding using UAVs to target American citizens on American soil, while I recognize the potential for abuse, I sort of see where he's coming from.
We already have policies in place that allow law-enforcement agencies to use lethal force against criminals (think SWAT snipers, for example). Why couldn't those same policies apply to armed drones? It wouldn't make sense, policy-wise, for the AG to tie the government's hands by saying "We would never, ever, under any circumstances use a UAV to target an American citizen within the boundaries of the United States."