O joy, o rapture! Metro has started random searches. Sounds like security theater to me, and I don't intend to be a part of it. (Gladly, I walk to work and most shops.)
If you enter a Metro station where a screening is taking place -- they come before the fare gates -- you have the right to leave, which I'll likely do. And I intend to have a copy of the following with me:
Spread the word.