eman - this has actually been going on since 2003 - their first attempt at this was to start filtering just the english language results and for one keyword "sex"
If you look at the browser bar - the &hl= term describes the language the results are in and you can certainly change it to see what the rest of the world (outside of the US, UK, CA and AU) sees - there is an amazing difference in "filtering" although Google themselves on another board called it censoring
Example:
Take that same keyword
http://www.google.com/search?hl=en&q...=Google+Search
and you get what the US sees
Now change the url:
http://www.google.gr/search?q=sex&hl=el&start=0&sa=N
And you see that the filtering isnt taking place
Its been progressing over certain words and phrases for the last 4 years and they must be playing with the filtering again as the xxx term keeps going between mainstream and porn - and has for at least 3 years that Ive followed that specific term in my spreadsheets