I think it's worth to mention here that Wolfram site also has a so called "Wolfram Programming Lab", which is basically a free access to Mathematica hosted in a cloud and not requiring registration.<p>Link to create and open a notebook: <a href="https://lab.open.wolframcloud.com/app/view/newNotebook?ext=nb" rel="nofollow">https://lab.open.wolframcloud.com/app/view/newNotebook?ext=n...</a>
It's just a blank orange screen with the text "Wolfram|Alpha Open Code—Tour" and a link back to wolfram cloud at the bottom of the screen for me (in Chrome).
I couldn't make this web page work either.<p>Anyway, I think what it's trying to announce is the new button included in Wolfram Alpha results. The button looks like a cloud with a right arrow inside it and when you mouse over the button, it adds the text “Open Code”.<p>When you click the button, it takes you to an in-browser Mathematica notebook containing cells for all of the different Wolfram Alpha results.