phhhhhhhhhhHHHHHHtt.... wah? O hai.
Actually, I don't smoke anything, or even drink these days. But this writeup at Wired of some fascinating research makes me think I should start ... if it were legal. It turns out not only does using pot not make you permanently stupid, it actually makes you smarter in one particular way when you're high - word association. It's a little more complicated than that, of course. And there is some reduction in short-term verbal memory among current heavy users. But overall, this is another piece of evidence that supports the decriminalization of marijuana. The harm caused by criminalization continues to far outweigh the harm caused by the drug itself.
On a strictly anecdotal basis, I've always thought the dumb stoner/hippy affect was a sub-cultural artifact. The whole "oh, wow, man" attitude may be induced by getting high, but its carryover to the rest of people's waking lives was a learned trait. Fortunately the sub-culture has mostly gone away, especially now that The Dead are dead.