[wp-hackers] WP_Query() for meta_value = Empty or Missing?

[Mike Schinkel]

Wondering if you guys can repeat your awesome performance in your answering of questions from yesterday.

I'm trying to use WP_Query() to query for a meta_value that may be empty or it may be missing.  As far as I can tell there's no way to do that given the parameters found here?

http://codex.wordpress.org/Function_Reference/query_posts#Custom_Field_Parameters

Am I missing something or am I going to have to dive into using posts_* hooks?

-Mike