[ubasu]

It seems there's a fourth edition:

http://www.scheme.com/tspl4/

Also, Wikipedia says that "Teach Yourself Scheme in Fixnum Days" is outdated in some parts:

http://en.wikipedia.org/wiki/Teach_Yourself_Scheme_in_Fixnum...

[sigzero]

TSPL4 covers RSR6 which didn't go over very well with the community. TSPL3 is probably the better bet there.