If you like Amdahl's law you may also like... http://en.wikipedia.org/wiki/Gustafsons_law

It is a more powerful expression of the benefit of scaling with parallelism. Principally, instead of scaling speed with respect to a fixed data size, you scale the data size with respect to a fixed speed.

Having more cores means you (sometimes) can have more data. You still need those parallel programmers with their parallel algorithms though :-)