Gnome-terminal (which I know do this) uses the following scheme:

If something starts with www or http:// it is recognised as a link up until the next illegal (in a link) char plus newlines. However if the last char is a . or , it is ignored.
in perl language somthing like:

@links = m/((?:www|http:\/\/)[anything allowed in a link \n]*)/ig;
for (0..@"#links) {
  $links[$_] =~ s/.$//;
  $links[$_] =~ tr/\n//d; #Remove inline newlines.
}
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