Electronic – arduino – Simplest way to upload sketches onto “hackduino” without having a arduino duemilanove

To be able to bootload code on the Arduino, the programmer must attempt to connect within about 3 seconds of the AVR coming out of reset. I the ArduinoBT I have lacks a connection that the traditional USB versions have, which allows the programming software to reset the Arduino by itself. In lieu of that, you must physically hit the button to do it yourself.

I cannot see how can I press the reset button on the Arduino during the upload when I have to type the PIN in a different window.

You should only have to type the Bluetooth passkey once, so after the BT module is paired with your computer, the computer should be able to freely connect, so long as it is powered.

The Bluetooth module and AVR are very separate; you can hold the AVR in reset, and the Bluetooth module will happily run along. If you're cutting power to the entire board to reset it, it may indeed be difficult to have the BT module come online, connect to it, and initiate programming all within 3 seconds.

While perusing the IOIO board link provided in the question, I noted that the board has some 5V tolerant open-drain digital output pins. Since the camera has built in pull-ups, as shown in the first diagram in the question, you should be able to connect the open drain pins directly to the camera. You will not even need the external transistors.

The current sink capability of the open-drain outputs is specifed at 20mA, which easily will handle the .5 mA mentioned in the question.

In this case, the camera "expose" and "focus" would be connected to open drain outputs, and the camera ground would be connected to the controller board ground.

edited to add:

I now note that the page you cited in the question, http://www.covingtoninnovations.com/dslr/CanonRelease.html, advises adding an optoisolator to the circuit if the camera will be powered by an AC adapter rather than the camera battery, as shown in the second diagram in the "Serial-Port Cable" section. That is probably a good idea. In that case, you could connect the optoisolator to an output pin on your controller board that is not an open drain pin, selecting a dropping resistor to set an appropriate drive current for the diode.