It took some experimenting, but I got Siri to read my Errands list by specifically saying, "Read my Errands List." I did not change anything in Accessibility for it to work.
Also, here's a really useful 4 minute video I found walking through more iPhone features. I learned a few things from this that I didn't know were possible (like creating a home button on the touch screen.) http://www.youtube.com/watch?v=f_aADB8k5nA
We expect to have our GTD & iPhone available in the DAC Store by this Friday. It focuses solely on the built-in applications (no 3rd party) to take advantage of what comes native to the iPhone. Hope you all find it useful!