I ran the whole rails source through aspell, got some ~4400 words which aspell suspected of being spelling mistakes and then manually went through the list and grepped for the words that looked like actual mistakes. Most of the changes are to comments, most are for actual spelling errors, a couple may be a bit debatable, like hoze -> hose ;)
I'm assigning this to actionpack as there is no component that covers the whole rails source and actionpack seems to have the most changes in the patch.
Let me know if I should split the patch up or if this patch is a bad idea.