Update: We just received confirmation from an anonymous source that Google is indeed working on this project.
We just heard from a retailer in San Francisco that Google also photographed the inside of their store about 2 weeks ago - after seeking permission to do so, of course. According to our source, the Google employee used a "specialized camera which he rotated to take the 360 degree shot." In addition, he also took shots "looking out of the store as if exiting." This last part makes sense if Google wants to use this sequence of images to simulate the process of entering and exiting the store.
Of course, scaling up a program like this would be a lot harder to do than having a fleet of cars drive around the country and take photos in what is now a mostly automated process.
Here is the image that Search Engine Land received from the New York-based retailer:
Given that Google is already using its Street View trikes in parks, university campuses and zoos, locations like large malls would seem like a more reasonable area to expand Street View to first. Taking Street View indoors does make a lot of sense, however. Stores and malls are the obvious example that Google could monetize, but the company could also use the same technology in museums or public buildings.
The problem with these locations, though, is that Google can't rely solely on GPS to create these indoor views. Maybe that's why the company decided to work with smaller locations first to try out different methods for creating reliable indoor maps efficiently. It is worth noting that there are currently only a handful of mobile apps that offer indoor maps.
We asked Google for a comment about this rumor and will update the story once we hear back from them.