I have a touchscreen laptop. I love it, but UIs like these would make me love it even more. Having information detail literally at your fingertips sounds amazing.
This seems like such a sensible idea to me, it makes me wonder why it isn’t commonplace yet. I hope it will be!
Windows 8 (Metro) used semantic zoom. It's been a while, but I do remember that one of the apps that used it very nicely was Photos. A search for "windows metro semantic zoom" comes up with lots of articles about semantic-zoom-aware GridView controls etc.
Why isn't it commonplace? I think that touchscreen laptops are still too much a minority, and keyboard + mouse + monitor are too entrenched, for anyone to seriously attempt it again for a while. (A shame -- I'm one of the few who really liked the Windows 8 Metro interface.) I think that phones are too small for it to really work well. I don't know why it's not more popular on tablets.
Something that would help speed up development of new interfaces would be applications having more extensibility in general. It happens so often that I come across a piece of software where I want to change just one thing, but there's no easy way to do it with plugins or extensions. The alternative is to create the software mostly from scratch myself, which is way too much effort that's just not worth it. Imagine what would happen if you could see all those small changes stack up, we could have so much more interesting functionality.
This seems like such a sensible idea to me, it makes me wonder why it isn’t commonplace yet. I hope it will be!