Nice work! How about using a variable resistor (or perhaps two in series/parallell) to get a more flexible adjustment of the times? And perhaps a LED that lights up so you can "dry run" to check the time between triggers?

Also, if you let the relay trgger the port for a second or two, that might allow for the camera to shut down between shots and be re-activated by the remote? (I havent checked if this works with a remote, but my 350D wakes up when I press the button)