All modern OS's and languages are based on the idea of progressive data latency. We write software explicitly to mitigate how slow it is to get the data you need. First we optimize to have the data in registers as they are the fastest, then RAM which is a number of clock cycles behind, then virtual RAM which is even slower and is on disk, then RAM caches which is an attempt to put disk contents in RAM for faster access, then an eternity later if we have to we'll go out to disk for the data we want. Then of course we have networking and bus data which is another matter.
Managing this pipeline is probably the major concern of modern systems and much of the time the computer gets it wrong and the CPU stalls. Multicore? GPGPU? Forgetaboutit, you're usually still stalled on data. This is the biggest issue with GPGPU programming (using all those beautiful state machines in your GPU). The problem? You can't get the data moved around quick enough to make it worth the while.
So, SSD worth while? You bet - for EVERY aspect of your system, remember data access is the biggest bottleneck in computers. I wish it were register flash, i.e. as fast as registers. If HP delivers memristors like they're promising maybe we'll get that. And note they'll have to rewrite operating systems to even work on such as system (and system software).
I'll also note that the GPU industry knows this, the problem isn't having enough cores, it's moving data fast enough.
