On the Sunday of arrival I and my roommate David went to 7-eleven for essential food supplies. We took a detour on the way and invaded the Nintendo of America campus. Visits into the buildings are only possible with an employee guide so this is the closest we will be getting this summer.
We did not find much. Beyond various signs the campus bore no markings of Nintendo. I was hoping for maybe a Mario statue but there was not even an occasional plushie on a window sill.
Update 2013-10: If you are still interested please consider reading through the overview of my internship.