It's been a while, so here are the updates.
First, we suffered along with the chair-constructed baby jail a while longer. Here is Philip peering out from the bars of his cell:

We now have a baby "fence" made by Little Tykes (I think) which allows us to gate off part of the living room. It has some toys on it, and I think it's nicer than a playpen because it gives Philip much more space and he can play on our floor. Plus, he still gets access to his game of DVD destruction.
Crawling is a definite success, the little bugger is FAST and motivated. Yesterday I watched him "back it up"-- a perfect, backwards crawl. This is an especially important skill when it comes to his cat-stalking. He will literally follow the cat around the room, trying to grab her, and giggling the entire time. I swear she is teasing him. She'll eventually let him win, and he'll pull her tail, or she'll sniff his face, at which point he giggles even louder.
We can tell that the pulling up stage is upon us. Philip understands there is a world existing above his head and he really wants to be there. He will pull his legs up from a crawl into the downward-facing dog pose, or he will try to pull up with his arms on the couch, me, whatever he can find. He also ignores any roadblocks we create, so if I try to limit his movement on the bed with pillows or my legs, he'll just try to four-wheel drive himself over them.
I recently met a new pediatrician, and have decided to switch to him. He runs a solo practice a few miles from our home, and has been a pediatrician for about 30 years. He's really wonderful and I'm looking forward to going to someone I like.
Of course Philip is still eating food other than milk, but more so than before. Last week I was eating half of an apple with him on my lap and discovered that he loved to chew on it. He would spit out the peel, and when I looked at the underside, I could see little teeth marks (which was incredibly cute). He also ate an avocado (smearing it everywhere), sweet potato, and licked a potato and some cabbage I happened to be eating. He also gnawed on some french bread. A few weeks ago his top teeth broke through, so he now has four.
Now, some new pictures
From above...
Chilling Out on Dad (I have no idea what the purpose of that blurry hand is, though)
One unhappy baby...
Until William cheers him up!
While we were eating on Sunday, Philip kept playing with his favorite (metal) spoon. (Not to be confused with his favorite wooden spoon). Then William had an idea...

Later that night, I was cooking (what was ultimately an unsuccessful batch of vegan brownies) while wearing him on my back in my mei tai. He thinks my hair is hilarious, which is fine and all...
until he pulls it! And when I yell out, he thinks THAT is even FUNNIER!