The reports are coming from all ends of the globe. Europe has reported a literal invasion of Mr. Mimes in certain areas, Australia reported Kangashkans runing across the street catching Pidgeys. While the US players are still mostly asleep, we are unable to confirm the rumors that packs of Tauros were spotted near the high ways.
A reddit user asked a question on /r/TheSilphRoad to confirm if he was the only one noticing the increased spawn rate, but as the discussion grows, it seems he is not the only one.
Why would Niantic increase the spawn rates over night is questionable, but it could be a sign of the upcoming Trade update. An effort to reduce the market converging around regional exclusives by the looks of it.
There is not much to say, but to recommend packing and going after the region exclusives today!
Here's a screenshot of Mr. Mime spawn spot in Europe:
Another one in Notre Dame:
Kanghaskhan in Australia: