One would think it obvious that libraries would fit into the GLAM network of relationships.  But to a great extent, I think the GLAM formulation is Wikimedia's own.  Although I often see a cross between libraries and archives, I know plenty of people in both fields that perceive themselves as separate.  Even with museums, and even with *librarians* in museums, many I've encountered see themselves as part of the special libraries sphere (i.e. libraries that are generally corporate, for-profit, or "other") and not part of the academic or public library world.

In this regard, I think Wikimedia can function as an ambassador to bridge more of the gaps between all those represented by GLAM.  I've begun to see that happen with the networking done by some of the Wikipedians-in-Residence among themselves.  There should be people pushing for Wikimedia program at the various conferences (unfortunately it's kinda late this year: the American Libraries Association (ALA) meets June 22-26, the Society of American Archivists (SAA) meets August 6-11, the International Federation of Library Associations and Institutions (IFLA) meets August 11-17, and and the Museum Computer Network (MCN) meets November 7-10).  

People involved with Wikimedia should offer to propose some kind of joint panel from multiple disciplines (GLAM Panel) to make presentations to the various societies which represent only one part of GLAM -- at the local and (eventually) national level.

At the very least, Wikipedians-in-Residence should make presentations on their jobs and their accomplishments to both large (national/international) and local organizations.  

Even if your institution does not have a Wikipedian-in-Residence, just circulating job descriptions or articles about such positions can help to spread and inform people about possibilities.