I found a site called MapJack via this post at Mapperz last week, but haven't seen much other comment on it. They provide a similar "immersive photographic" view of the world to Google Street View, but they include data from some locations where you can only walk (not drive), and some that are indoors - including a tour of Alcatraz. Currently they just have a beta site with coverage for San Francisco. The user interface incorporates some very nice ideas.
One of most interesting aspects of this for me is in the "About MapJack" page, where they say:
Mapjack.com showcases a new level of mapping technology. What others have done with NASA budgets and Star Wars-like equipment, we've done on a shoestring budget, along with a few trips to Radio Shack. Specifically, we developed an array of proprietary electronics, hardware and software tools that enable us to capture an entire city’s streets with relative ease and excellent image quality. We have a complete low-cost scalable system encompassing the entire work-flow process needed for Immersive Street-Side Imagery, from picture gathering to post-processing to assembling on a Website.
This is just another example of people finding ways to bring down the cost of relatively specialized and expensive data capture tasks - it made me think of this post on aerial photography by Ed Parsons.