Though the concept is not new, these projects are really interesting, making 3d-buildings out of pictures, and if you look who is behind all of these you'll find a lot of people with a lot of experience in it.
the photosynth similarity is actually addressed in the youtube comments:
"The major differences are that we create a dense 3D model and in contrast PhotoSynth uses the images for visualization. Additionally we can handle orders of magnitude more data millions of images compared to thousands. We can handle more disturbances in the data."
I wonder what technology Google's gonna buy next and rebrand? They'll definitely want this for their maps. Google's really good at catching things before everyone's heard of them and developing it to something useful (although not always profitable).
Anyways, I expect to be able to do 3D visits to Amsterdam on Google Earth in 3 years or less. Although I guess a lot of cities are more known for what you can do there instead of what you can see.