Repeat after me, if your app doesn't scale it is YOUR fault, not a language, platform or framework. Scalability is about design and implementation, not what tools you use.
I think I understand why the initial design/technology decisions would rarely make it to a product that has to be largely scaled. This makes perfect sense for almost all cases.
Do you think that there are technologies that are inherently more scalable than others, so if some body was initially choosing them would stand more chances to scale up in a non painful manner?
That said, I would say that languages and technologies that help you achieve a more modular design will help you scale more. This makes it easier to tear things out and move them around so you can alter your architecture much more easily than you would otherwise. And of course efficiency (in terms of code performance) doesn't hurt either, but I wouldn't choose something on that alone. If you can have efficiency and modularity, so much the better!
Nowadays, we have fancy stuff like Resque for background jobs, Passenger (aka mod_rails) for serving up Rails content, and a plethora of NoSQL databases.