FWIW, I'm strongly opposed to this. (And I did a double-take at Barry's post: is it April Fool's Day already?) C++ isn't Perl; we don't use Unix shell globs like that. In C++, curly braces have a couple of different meanings (code block, initializer-sequence), but not "shell glob."
Compare:
using A::{X,Y,Z};
and
enum A {X,Y,Z};
Notice, both are comma-separated brace-enclosed lists of names. Also, in both cases, each name is introduced into its parent scope.
A slight alteration we could consider would be:
(drop the extra ::), and then perhaps that seems more natural?
It's a common coding style to have a big block of usings at the top of a .cpp file. This feature would significantly shorten that block.