I think that it's a script-generated spambot, even though I haven't found anything to exactly verify this yet. And I think that the reason for the explosion is that it's not only spidering Interest-Data, but communities off of Friends-Data too. Livejournal actually allows for the information to be used by bots.
As satisfying as I'm sure fervently typing 'GET OFF MY FUCKING INTERNET!!11oneone1' in response to something that isn't going to tell you to stfukthx in return is, it's probably just spreading it. Which, of course, serves everybody right. Or something.
The kind of Internet Outrage! in the threads amuses me anyway.