We cut nature up, organize it into concepts, and ascribe significances as we do, largely because we are parties to an agreement to organize it in this way — an agreement that holds throughout our speech community and is codified in the patterns of our language...
Many have taken this to mean that he believed that language helped control and shape the way we think (a view originally put forward by Wilhelm von Humboldt) but others suggest that Whorf was never really making such a bold claim.
Whatever the rights or wrongs of this, there has been a lot of interest in the idea that the languages we speak, the words we choose and the grammar we use might have an impact on how we view the world. This week's BBC news website carries an account of Professor Keith Chen's research into language and economic habits, wherein he suggests that speakers of languages that have a strong "future time reference" (i.e. use a separate tense to indicate future time) are less likely to plan ahead in terms of money and health. As the BBC story puts it, "... if you speak English you are likely to save less for your old age, smoke more and get less exercise than if you speak a language like Mandarin, Yoruba or Malay".
According to Chen, languages either have a strong or weak FTR (future time reference) and those with a strong FTR tend to separate present and future, making it less likely that the speakers connect present actions with future events. In other words, the stronger the difference between your language's representation of present and future, the weaker the speakers' ability to link present and future. He argues that this then leads to an inability to plan ahead.
Of course, this is a very difficult idea to prove, particularly if you're not actually a linguist (Professor Chen is primarily an economist), and Professor Geoff Pullum cautions against taking the research at face value in an interesting response on Language Log. One of his key points is that Chen is mistaken in claiming that English has strong FTR, given that we tend to use the present tense (I am going to play football to morrow) or modal verbs (I will play football tomorrow).
The story has been picked up elsewhere, including here, where other links between language and thought are discussed, and in this debate between Lera Boroditsky and Mark Liberman.