URL filter doesn't properly handle trailing punctuation

As I understand, the filter that generates links from URLs tries very hard to leave punctuation (or parentheses) out of links, which is very helpful when the URL is at the end of a sentence.

http://drupal.org/node/176282#comment-625177 alerted me to the fact that this protection doesn't extend to the colon. When a URL is followed by a colon, the link will contain the colon and very likely break it.