You certainly don't need to know scheme to read SICP. You learn it along the way.
What did you use to make the pdf? It's not a good tool because the resulting text is a bunch of bitmaps.
I have a strong feeling that clojure is today's scheme. But I should probably just run away.
Clojure is not as simple and as elegant as scheme, but it's still cool. I don't think it would have been this easy to learn clojure if i didn't learn scheme first. All my knowledge about recursion, FP and data structures i learned while playing with scheme. I've never written anything other than toys with it, but it was a very good introduction to lisp, and now im learning clojure and its fun as hell!
Sorry, but I just can't call something that lacks tail call optimization a Scheme :)
Not to say that Clojure is bad or something.
I feel like Clojure is CL-flavored Scheme. It's a lisp-1 with strong emphasis put on functional style (except for TCO, but loop/recur are a good explicit workaround) and then it has tons of libraries (via Java) and CL-style macros and more syntaxy things (literal maps, vectors, etc). It's sorta a cool lispy mashup.
There are currently some big developments happening in the Scheme community. Definition of the new Scheme standard is currently underway and there is a lot of motivation to produce something that will bring the community together. Check out recent activity on c.l.s and on the r6rs-discuss ML.