Programistan is the place where the IT department has placed files/pages that everyone in the company needs to update or change but that no one in the company can access. It's buried under some alphabet soup programming language/code/bleck that only Mitch in IT can change.
"I need to change some text on the website. Who do I ask about that?" "Aw, man, that isn't happening today. Only Mitch can do that; those files are in Programistan."