Today, I went down Charing Cross Road and visited Santa's Ghetto, the exhibition/sale of "subversive"/"underground" art, including works by Banksy, Jamie Hewlett, Jamie Reid and various other stencil/graffiti artists. There's a bit of a review here, and photos here.
I picked up a copy of the new Banksy book, Cut It Out, which has photos from a visit he made to Australia; then I guess those Banksy rats along Brunswick St. may not have been ripoffs. (The "Wanksy" stencils, however, are another guess.)
It varies depending on context, and means either "pretentious wankers who think they're cooler than they actually are" or "people who are into non-mainstream culture". It was originally used by troublemakers on an indie-music web chat room (not unlike the alt.tasteless invasion of rec.pets.cats in context), who saw no difference between the two contexts.
It is. His previous two books, "Existencilism" and "Banging Your Head Against A Brick Wall", are around in shops in Melbourne (try looking in the Brunswick St. Bookshop).
All three books are smallish and consist mostly of pictures and smartarse quotes/remarks.