I’d rather they not, it’s much easier to theme right now.
Probably after 1.3 for something like this.
Yes, please as little widgetizing as possible. Keep code out of themes. Keep BP aimed at content producers and web designers (html/css), don’t turn it into Squarespace.
Well, if WP 3.0 supports it then BP will support it, since it runs on top of WP. I think it’s gonna be a theme thing, much like the widgets. If the theme designer adds support for it, then your users will be able to use it. In a MU setting this just makes sense, cause they have no access to theme code, so can’t build their own custom navigation.
It is definitely a theme thing. Same as the way the custom header has to be declared in the theme itself for it to be accessible in the backend.