These two (generalized Pod comments and C<is doc> are both better than my suggestion. :) They require less typing, so documenting at a finer granularity (e.g. object attributes) is easier. It would provide an opportunity for very thorough auto-generated documentation as outlined in Mark's 2007 post
In Perl 5 I hate having Pod interleaved with code, since it is usually mostly /user/ documentation and so just gets in the way. Having normal Pod elsewhere (at end-of-file or in a different file) and keeping API Pod docs inline (and having tools which might merge the two into nice HTML if desired) would be the best of both world. As for "#={ Pod }" vs "is doc", since I've been working on Perl 6 highlighting in vim, the first difference that comes to mind is that highlighting the #={ Pod } form like other Pod (with L<inks> looking distinct n' all) is easier and makes more sense since it's not just a normal string (which might have come from anywhere). Highlighting the other form would be a special case that might be hard to detect, and arguably shouldn't be, since it is just a string.