Echoing all the previous statements, I gave two weeks' notice when I left my first real job (Microsoft), and they immediately walked me out the door. In this case they weren't jerks about it-- my manager even apologized to me and said if it was up to him they'd've let me stay, but said it was absolutely iron-clad policy that he couldn't change-- but yeah, giving even more notice than that seems to be advice that could only come from someone tremendously naive who has never actually worked in tech.
I've been at companies like that, when I told my manager I was leaving, he was basically "lets wait to tell HR until X date so they don't walk you out and you can transition your stuff". Didn't bother me, as the benefits mentioned in article applied.
