Additional function in JQL; ability to search issues where fixVersion has a release date or not

I am hoping you would consider to implement a new function in JQL. The intent is to be able to search for issues where fixversion's release date is/is not defined.

The goal of the function is to create a search of issues among multiple projects to find all issues which has been scheduled, hence they are the active issues. It would be an alternative to creating a filter based on fixVersion name, which would required a lot of updating.

I also see there may be issues with greenhopper parent-child versioning, but am not sure how is should be handeled...