I tested (string->number "#x10") against my usual test suite.
Racket, Gauche, MIT, Gambit, Chicken (with or without the numbers egg), Scheme48/scsh, Guile, SISC, Chibi, Chez, SCM, Ikarus/Vicare, Larceny, Ypsilon, Mosh, IronScheme, NexJ, STklos, TinyScheme, S7, Rep, Elk, UMB, SXI, Sizzle, Spark, Inlab, Owl Lisp, Scheme 9 all return 16.
Bigloo, Kawa, KSi, SigScheme, Dream, BDC, XLisp, Schemik, VX return #f.
Shoe, Oaklisp, MScheme, Bus don't support string->number.