Not exactly the same results than Norvig's version (>>> correct("speling") -> "sling" / "godd" -> "god") but I tested the Ruby version linked on his site, and it yields the same results.
I.e: Your / my "correction" of pg's version give "spelling" and "good".
And pg's vanilla version for (correct "yellow") gives "fellow".
Sorry, I noticed your post after I posted in haste. Nice work - 12 lines is still darn impressive. Followup with a comment if you use Norvig's test program and notice any other issues.