What does it mean to "walk the wall?"

Solution 1:

"Walk the Wall" can refer to a kind of Stand-Up meeting in which the group goes through each item of work in their "wall" and talks about its progress.

http://fabiopereira.me/blog/2011/02/28/walk-the-wall-stand-up-meeting/

Solution 2:

Walk the wall is a military term for "guard a border, watch those on the outside, keep those on the inside safe".

Solution 3:

Walk the wall is used by various consultants for reviewing internal ops/workflow/org structures. Each leaders has assigned workflow and review it all during a "walk the wall" session - literally walking thru the workflow.