I just *like* the infinite scrollbar idea a lot. It doesn't apply to everything - like I probably wouldn't use it for basic web searches if I was looking for something specific, and I rarely read long web pages using the middle-click thing in Windows that most of us would rather turn off if we could, but the idea of scanning a bunch of images this way or news information, or anything where we need to really see lots of examples - you know where you end up going through and paging in search results, or changing the results to 100 per page? This is perfect for.
I can think of other examples as well - chat logs for instance. Imagine if you could go through the last year of a public chat room this way? Or maybe even blogs themselves - this post is just another in a series that goes back three years... maybe my archives page could use an infinite search bar as well? It'd be very cool...
Just thought I'd add my two cents in.