"we're sure it's only a matter of time before folks devise some slightly more useful means of exploiting this interesting find."

Here ya go!
(Dependencies: UNIX, Bourne shell, netcat, gxmessage)
And seriously, this should work, but having no TiVo, can't confirm. Let me know what happens, if anyone tries it. I recommend a Zaurus or Nokia IT, but with the awesomeness of the SDK, I'm sure someone will have X, GTK+, and gxmessage running on the iPhone any day now...

Code:

#!/bin/sh
while true ; do
  response=`gxmessage -center -borderless -nofocus -print -buttons "CHANNELUP CHANNELDOWN PLAY PAUSE FORWARD REVERSE"`
  echo "IRCODE "$response |nc tivo.example 31339
done