(English explanation here.)
[Edit 4/8/05 09:30 PDT: Well, looks like the meme got slashdotted into submission. See this entry for details.
One minor note. One of the Russians commenting in that thread said the following:
сударь, вы флэшмоббер!
I don't remember what сударь means, but I know вы is we, and флэшмоббер pronounces out, somewhat similiar to 'flashmobber'. (It's not perfect, but transliterations seldom are.) Flashmobbing indeed. :)
I need to go back to learning Russian one of these days.]