The retirement of the SR71 indicates to me that there is some sort of undisclosed recon plane flying for the US. I understand the costs of flying the SR71 were high, but I can't imagine the US would abandon the ability to fly on-demand recon over heavily defended airspace, a task the SR71 was uniquely suited to handle. Yeah satellites can do a lot but they aren't everywhere at all times. And yeah, the U2 can still take some fine photos, but it doesn't penetrate heavy defenses like the SR71 does.
So I think there's probably something else out there. My guess would be some sort of un-manned low observable platform. I don't know if this "Aurora" thing is real or just sci-fi (for example, if why would a low observable have to be so darned fast?) but there's probably something out there.