It's somewhat like Google Earth but with paintings on the walls of museums. You can pan the room, zoom, find out information about each painting, see museum floor plans, post links of pictures to social networking sites, and build your own art collection, if you have a Google account.
The ability to build a collection of online art is very cool. I hope you check out the Google Art Project and please share it with any art teacher you know.
Here is one example of a van Gogh I like.