Unless this is a huge "opening day rush", it's a really, really impressive number, particularly considering that the domestic (meaning Japanese) selection at the JiTMS is miserable at this point; my wife and a friend spent about an hour searching last night (man, it was funny to see them get fired up every time they found a group they were looking for), and probably 3/4 of what they searched for wasn't there; Sony, who's holding out, has a HUGE number of very popular groups under them, and the JiTMS barely has any domestic albums more than a few years old.
The import selection is fine (probably based on existing iTMSes), and I expect the lack of older stuff will start to fill in over time, but nearly matching the "first million" rate of the US Windows release in a country with less than half the population and an anemic domestic catalog is pretty darned good.
This puts Sony in the interesting position of either shooting their music division in the foot by holding back their catalog from the iTMS to try and boost hardware sales, or shooting their hardware division in the foot by selling songs at the iTMS. It's probably not a huge difference to them either way, but it's pretty much a loose-loose situation.
Also, on Sony vs. iPod sales:
Last I heard from Japan Sony's flash-based players were outselling the Shuffle, but the hard disk based iPods are doing better than Sony's HD-based players. I do wonder how the iTMS may change this.
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