I am told it's been doing this for months - but I opened Google Earth this morning and it looked different - so I guess it has updated - I'm now on version 188.8.131.5242
I flew to some coordinates - so was looking at satellite imagery directly from above - so it was completely flat - which I'm used to...
Then I dropped Pegman on a road to dive down into street view...
Then clicked the button to exit street view - which left me with an oblique view across the landscape.
In that view, when I pan across the landscape it actually looks 3D!
Hills are hills, valleys are valleys etc and there's true depth there as well - it's rather cool
Looks like they've added a polygon based bump-map under the flat satellite imagery, and the imagery bends to conform to the map in real-time as you move around
(You can sometimes see some of the polygons - triangles - above the satellite imagery - which is what confirmed my suspicions)
I like it