Parallel programming languages which look deterministic? Are there any programming languages where the system parallelizes the program without any noticeable differences for the programmer? 

That is, the programmer writes a linear, deterministic program, without any additional tags or meta-data, and the underlying system parallelizes all of the work.
I'm not sure about the "without any additional tags or meta-data" part, but I know that recent versions of Matlab make it pretty easy to parallelize your code by simply adding the "par" keyword to your for loops (see the Matlab help for more info).

This is as close to having no "noticeable differences for the programmer" that I'm aware of.