On that other blog someone said it was a BA A321 and I have to concur. The length :: wingspan is almost exactly 4 :: 3 which means it can't be a 330 and of the 320s only the 321 is close.
You can't calculate the altitude without knowing the altitude of the Google plane, but if you use the scale diagram in the lower left of the map it's clear that the plane obscures about 243' of ground from tip to tail. An A321 is actually 146' long so that makes it about 60% of the altitude of the Google plane.
If the BA plane is at about 6k (as someone else speculated on the same blog) that puts the Google plane at 10k. Pretty impressive photography to be taking photos of things 2 miles away with enough clarity to see individual cars and even pedestrians.