There have also been a few moans about the formatting of code, so this is just a test

int main(int argc, char *argv[]) { printf("hello world\n"); return 0; }

Indeed it does seem to want to transform \n into br / but also seems to leave behind the \n inside the pre tags. Doh!

Update: small tweak of the code and all now seems much better. Of course there are probably problems elsewhere, but so far it all looks ok. For future reference, i changed the default in wpautop from $br = 1 to $br = 0 (look in wp-includes/functions.php)