Mark,
In the canonicalization guide link you sent me, there is a link to Matt Cutts' blog www.mattcutts.com/blog/seo-advice-url-canonicalization/ where he talks about it. In that blog he posts:
Q: So when you say www vs. non-www, you’re talking about a type of canonicalization. Are there other ways that urls get canonicalized?
A: Yes, there can be a lot, but most people never notice (or need to notice) them. Search engines can do things like keeping or removing trailing slashes, trying to convert urls with upper case to lower case, or removing session IDs from bulletin board or other software (many bulletin board software packages will work fine if you omit the session ID).
This makes me think that doing a 301 redirect and a rel="canonical" for lower case is not needed.
I'm conflicted again.