Another useful feature might be to be able to choose a different template file for some pages; blog pages would use a template different from the home page, even if both are managed in the same repository, etc.

Well, that would probably be fairly easy to add if it used pagespecs to specify which pages use the non-default template.

Hmm, I think the pagetemplate hook should allow one to get close enough to this in a plugin now.

See also: Allow per-page template selection -- same thing, really.