I think route9's firewalk did this back when I had dial up.

Yeah. Well, I actually wanted to write about tcptraceroute program originally, but then discovered that traceroute on one of my systems had the -T flag. So I thought, wow, traceroute now can use the tcp protocol. That's why I wrote "was added recently" because I hadn't seen the -T flag before. It turns out that that system had the http://traceroute.sourceforge.net/, while my other system had the ftp://ftp.ee.lbl.gov/traceroute-1.4a12.tar.gz, which doesn't have -T.