Using the forthcoming panorama viewer for Google Earth it is possible to embed 360x180 degree panoramas inside of buildings and thus fly inside to look around. The movie illustrates this concept with the Tate Modern, st1:cityst1:placeLondon</st1:place></st1:city> - we first fly around the 3D model and then 'step inside' to view the Andy Warhol exhibition.
The viewer is almost ready to roll, we just need to find some time to write the tutorial and then upload the file to edit on our server...