The .mobi Registry reports in a press release that people from more than 100 countries have registered over 100,000 .mobi domains in the first four days of the domain's general availability. They state that this demonstrates the great demand for these domains and offered this comparison:
In contrast, it took ten years for the general public to register 100,000 PC-based domain names in the early days of the Internet.
I think that's an apples-and-oranges comparison, but it's an interesting one nonetheless.