During my San Francisco trip December 2011, while walking on Valencia Street and waiting for my order from Udupi Palace (all veg Indian cuisine) located just around the corner, I saw a sign for this place. What a nice find, because I like fresh pressed juices. Here's my Sidewalk Juice review.
It's a brightly lit place with an order window. You can't walk inside. Just order at the window, pay (cash only), and enjoy your juice. There are a couple benches on the sidewalk for sitting. Very easy.
The menu features smoothies, fresh juices, and kombucha. I got the "green energy" juice which contains spinach, kale, apple, lemon, ginger, parsley, celery, and cucumber. $7. Good stuff.
A good place to get a fresh juice to go.