[larrydavid]

Pinterest does scroll downwards (infinite scroll as well). And he's right, it prompts the user to scroll down out of curiosity. IIRC Apple have employed this technique in the most recent update to the App Store, except you scroll horizontally.

In regards to the OP, I don't think the examples are related at all. The Pinterest example is more of a functional design choice (which I think works quite well), while the other two are purely aesthetic.

I agree with you on your second paragraph, the Delicious and ALA examples are simply a way to try and look a bit different. The A List Apart logo design choice caused quite a stir when they unveiled the redesign a few months back.

[manicbovine]

The landing page for Pinterest does not scroll. In fact, the png itself is cutoff: http://passets-ak.pinterest.com/images/signup_splash/loggedo... . Perhaps you're logged in.