Likos, re-read 2nd sentence of 4th paragraph of the article you linked (not counting italicised prologue) :-)

Basically the application can "fork" off a number of sub-processes and each sub-process can use its own 2 GB of data memory, so if you need 8 GB, you just fork 3 times.   Kernel memory is shared but you don't use that for data - each new process has just a small kernel footprint.   That 2 GB of kernel ram can support many dozens of processes, each with its own 2 GB of data.

Poser 7 can use a second thread for rendering if you set it in the options.