I have no idea who they are (since I can't read Japanese), but hatena appears to be some sort of Japanese social bookmarking site, and I'll often find hits from them in my referrer logs. One of the members found a newly-issued Japanese translation of my book, which opens up a whole new audience to my obnoxious personality.
Stumbling across the Japanese edition was a bit of a surprise. I mean, yeah, the book contract has some paragraphs about translations, but seriously, who actually expects their book to be translated? That's just standard book contract boilerplate stuff.
What next, a movie deal?