Beaker already displays the number of possible systems a recipe can run against. When trying to troubleshoot why a particular recipe is remaining in a queued state (and other situations), it would be handy to be able to see the list of systems that Beaker believes that recipe can use. This could be implemented as a link, or expanding panel, off the Possible Systems: # line in the recipe display.
Now that we can search systems by XML filter, this should be pretty easy. We can just link to a search for the same hostRequires as the recipe is using (perhaps augmented with the distro tree ID as well).
*** This bug has been marked as a duplicate of bug 607531 ***