I found very nicely done introduction to OpenCL by ATi and I want to share it with anybody interested:
ATI Stream OpenCL™ Technical Overview Video Series (http://developer.amd.com/documentation/videos/OpenCLTechnicalOverviewVideoSeries/Pages/default.aspx)
OpenCL is technology easily usable with PowerBASIC.
Petr
Side note: The tutorials are very good, but the initialization of device described there is obsolete and works no longer on NVIDIA or ATi cards. That is the danger of relying on "implementation specific behavior". Correct method is shown in PowerBASIC examples (http://www.jose.it-berater.org/smfforum/index.php?topic=3327.0).