It annoys me a bit that people talk about scaling problems as being brand new then. A lot of the first generation of dotcoms had them too (Amazon, eBay, Yahoo, etc).

In general they were solved similarly - build custom middleware and go as distributed as possible.

Now I realize that's a simplistic answer to a very complicated problem but really guys, this isn't unprecedented and the hardware is a lot more capable and cheaper than the 1997 equivalents.