Is version 15.1 with improved multithreading now shipped (and is there a place at the Gauss website where I can find the latest version available?)?
GAUSS version 15.1 is now available for download. Parallel for loops, using the keyword threadFor now create as many threads as the machine has cores (or the number of iterations of the loop if it is smaller than the number of cores available) by default. A maintenance release of 15.1, version 15.1.3 is scheduled to be available next Wednesday (May 13th 2015).
Your download account shows the latest version of GAUSS that is available.