The big news: He pooped in the potty!
He didn't want to do it, but he did it. He likes a little privacy when he poops (who doesn't?) so I took his pants off and I took a shower. He sat on his potty chair and did his business as soon as I was busy washing my hair. Of course, we celebrated his big success before I resumed my shower.
We were away from the house for nearly twelve hours today. My son did not wear diapers or pull-ups because I dressed him in his big boy underpants. I packed extra clothes and extra underpants, but I was very nervous.
He didn't pee in the carseat and he peed in an unfamiliar house on a regular toilet without a toilet ring. He also kept his underpants clean & dry all day until around 7:00 or so. He caught himself mid-accident once and called for me to take him to the potty. He had two accidents later in the evening, but it was well beyond his normal bedtime and I think he had forgotten that he was a big boy now.
All in all, I'd say that potty training is still going well. I hope tomorrow continues this trend.