The key is to send setTimeStyle:kCFDateFormatterNoStyle to the dateFormatter. That sets the dateFormatter so that it will only format the date and not output the time:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setLocale: [NSLocale currentLocale]];
[dateFormatter setDateStyle:kCFDateFormatterShortStyle]; // or whichever style...
[dateFormatter setTimeStyle:kCFDateFormatterNoStyle];
NSString* dateString = [dateFormatter stringFromDate: [NSDate date]];
This gives me the following output:
12/18/09