Yeah, that's the crux of the issue right there. I can't change the default to utf-8 because it would cause problems with existing installations that use a lot of special characters. New installations could and should be done this way.
The only real way to do it is in an upgrade where each post can be converted to utf-8. The upgrade will be a bit time consuming as it will have to convert each post, so it will need to be on a major release number and not necessarily a bug fix.
As a side-note: when my vps was recreated to use FC5 I was updated to MySQL 5.0.something and all data converted to utf-8. I haven't seen any ? but it's possible we never used the extended symbols.
