Many of the modern day unix concepts still are the direct result of the pioneering work of those making unix back then. So a big thank you from me to K. Thompson, Ritchie, M. D. McIlroy, J. F. Ossanna, R. H. Canaday and B. Kernighan and many more.
I'm not sure of August 1969 but the media seems to have declared it that way so I'll join them. [news.bbc.co.uk...] :
Think then what the Unix operating system deserves because in August 2009, it celebrates its 40th anniversary. And it has been in use every year of those four decades and today is getting more attention than ever before.
Work on Unix began at Bell Labs after AT&T, (which owned the lab), MIT and GE pulled the plug on an ambitious project to create an operating system called Multics.