When I read the Slashdot article, Things To Do Before You Die, one particular bit of information jumped out at me:
Lu Xun writes "A group of British scientists has brought some meaning to our lives by providing a list of 100 scientifically-oriented things to do before you die. The suggestions include 'joining the 300 Club at the South Pole (they take a sauna to 200 degrees Fahrenheit, then run naked to the pole in minus 100 F) or learning Choctaw, a language with two past tenses - one for giving information which is definitely true, the other for passing on material taken without checking from someone else.'"
I had no idea if the bit about Choctaw languages was true — in fact I'm quite sceptical about this kind of broad statement when I see it on the net — but I really wished it was true. It would be incredibly useful to have a grammatical construct to distinguish fact from hearsay, without having to resort to phrases like, "or so I heard", or "someone told me that".
Digging through the comments, AhtirTano suggested that it was more complicated than the way it was presented: there are indeed two past tenses, but they indicate how long ago something happened (less than about a year ago, or longer than that). At the same time, suffixes called evidentials indicate whether the information was directly experienced by the speaker, or whether it was indirectly acquired. This account seems to be be supported by this page on Choctaw grammar. I find it really interesting that languages diversify in this way, and seem to have such different ways of encoding the world. I can understand that the environment you happen to be in might affect how finely you discriminate between certain kinds of things (like types of snow — that other linguistic chestnut), but when the differences are in distinguishing how you came by information, it's difficult to see why that shouldn't also be important to people in all language groups.