Anyone know how accurate these are? They're pretty interesting to look at.

They're "estimates" not acounting for wind.
Enough said.

They should be reasonable on the hill segments. The steeper the better.

Way low. Without knowing the wind the estimates are useless.

If they were accurate, you'd be watching me win mountain stages in the tour. Across the board, the estimates are 50-100w high

The lightning bolts are when I'm actually using a PM

I think the answer is it depends on the ride. I just did a couple quick comparisons of two vastly different rides.

22 miles time trial race (C-130, Dover DE) - completely flat
Strava power estimate: 231W
Wired Powertap: 233W (not in the Strava file)

34.5 mile group ride (9 guys working mostly together), rolling terrain, 20.5 mph ave.
Strava power estimate: 201W
Wired Powertap: 161W (not in the Strava file)

Looks like Strava over estimates when there is any drafting involved. I've found it to be 10-15% high on most of my solo rides... 20% or higher if I'm riding with a group.

Do you have your weight and bike weight set accurately?

= smoking gun.

Yep