I should know, that's my dayjob :)
I had a look at your profile and it looks like you're doing some very valuable work. I was rather hoping for some examples which didn't involve JavaScript, though.
The term of art is "inherently sequential" problems (vs "embarrassingly parallel").
In addition, the programming effort gets untenable quickly due to Amdahl's law when the amount of parallelism increases. Eg. if you have 100 cores, even if only 1% of work in your program is sequential, your performance goes down the drain. Currently we're in the comfy phase of the curve with few cores...
We've been making good progress with parallel-minded reimaginings of programming languages and computer architectures on one front: GPUs. On the CPU we are saddled with the inertia and backwards compatibiltiy lock-in of tools and culture (witness lasting use of C++ as a tool to write parallel software)