In the Capital yes. In the Capitol, no.
In April 2008? (has it been that long?) there was an open carry dinner at the Outback Steakhouse where 7 armed people and their guests enjoyed each others company for nearly three hours without being interupted. There's even a picture of us floating on the forum somewhere. Give me some time, and I will see if I can't link it to this post.
Here's your link.