Null as match sort of deal

[Corey Tisdale]

I'm scoping out the simple faceting for a project we have coming up,  
and I am wondering what the best way to achieve the following would  
be (if possible). We have some facets where the presence of some  
value (in our current prototype on non-solr we use null, so we call  
the setup null as match :) constitutes a hit all of the time (where  
facet=x or facet=null) and on some facets constitutes a not match  
(facet=x only). Can out of the box solr faceting support something  
like this, or can it be done with a light massaging?

Thanks!
Corey