add filters for Found In and Integrated In fields in the Bug work item, similar to what exists for associating a build to a test plan in MTM
generally, make it easier and provide more flexibility in the creation and management of the global lists that feed these drop-downs.
The specific situation that is problematic is if you have a team project that is largely scoped... and you would have lots of build definitions and lots of builds being executed.
need something more recent and accessible than this: http://blogs.msdn.com/b/jpricket/archive/2006/09/05/how-to-filter-the-build-completion-event.aspx
alternative - make writing to the global list part of the build process template through an activity