Build-a-Bear building a head of steam

Build-a-Bear's online virtual world, buildabearville, which I wrote about here and on Gamasutra, hit 1 million users it's first month, and recently 2 million (it's less than 3 months old). They are also adding celeb appearances with kids from High School Musical and the like.

Phenomenal. How many other MMO/VW's are going to sneak up and surpass the traditional games industry?