I am also looking to add a location field to the register and comment forms. Is there some help out there on how to do this?

There are hooks in both the comment form and registration form that can be used by a plugin to add new fields, so all you have to do is write a plugin that does what you want to do THEN use the information you get when you publish the comment or somehow display it with the user profile (which is only available to the user and other blog members in the back office - no public profiles AFAIK).

Off the top of my head I'm not sure how one would actually use the content of the extra field when displaying a comment, but it might be quite easy.

Anyway I know my Turing Test plugin uses both the previously mentioned hooks to add an extra text field. After that I use the content to see if the person has passed the test or not. If they did then the comment or registration goes through, and if not it doesn't. That is a different end result than displaying the extra info yah?