Should weblogs correct themselves?

Sometimes you see incorrect information in a weblog post. (“Alfred Hitchcock, director of Casablanca...” or “Safari doesn’t support PNG files...”)

When it happens, and the information is corrected (often in the comments), should the weblogger update the original post? (On the theory that the original post is more likely to be read than the comments.)

Is there a difference between various types of inaccuracies? For instance, mis-stating the director of Casablanca (it’s Michael Curtiz) is probably not a big deal, but mis-stating Safari’s support for PNG files could lead people to thinking something incorrect which could affect their actions. (They might use GIFs in the mistaken belief that it’s necessary for Safari compatibility.)

I lean toward thinking that the original post should be updated, because people don’t necessarily always read all the comments. But I wonder what other people think. Maybe comments are enough?

P.S. To be clear, because I know people skim: Safari does indeed support PNG files.