There's going to be a ton of tweets about the #madebygoogle event. I'm putting all the info on the Pixel 4 into one article (currently ~2.7k words) and will post any new findings from on the floor/with the demo devices in this thread.
Wow, I didn't think they would actually talk about Live HDR+ today. Thanks to @cstark27 for his help on uncovering that!
That Pikachu Soli demo is in the live wallpapers app. 
Can confirm that Screen Attention and Live Caption are there. No new Assistant driving mode.
Pixel Themes, too.
Updated Pixel Launcher with the swipe down notification gesture is there
Frequent Faces is there, as we first reported. CC @cstark27
Strangely, the infinity focus option in Night Sight is missing.
Google One offer expires April 15, 2021.
Car crash detection is there. For some reason they didn't talk about this on stage.
No 3 free years of unlimited Photos storage in OG quality. Just cleared app data and didn't get any message on it.
The Android 10 Quick Wallet access gesture isn't there. It's still mentioned on the Android 10 website but it hasn't rolled out on any device yet.
Here's Continued Conversation in Settings > Apps & Notifications > Assistant and Google Assistant settings. No mention of to raise to talk.
Previously unseen game made by Google in Unity to show off Motion Sense.
Dev option to force 90Hz at all times
Option to automatically open to the last used screen after face unlock.
New "personalize using app data" privacy setting. Not entirely sure what it does yet.
Face unlock settings.
Here are the font and icon fill options that aren't present in the leaked versions (because the overlays aren't there in the Pixel 3/2 system images).
That's all from me for now. Gotta go play with other devices.
Music ticker on ambient display and lock screen.
Pixel Neural Core has an upgraded TensorFlow processing unit and powers features like Face Unlock, Frequent Faces, Recorder transcription, and other ML-based features.
Speaking of Frequent Faces, it works by detecting faces in photos you've taken and then, if you take photos of someone fairly frequently, Top Shot will recommend those photos the next time you use it.
Audio Zoom doesn't seem to be present, though I was told there is improved directional audio recording.
There's also a separate app/game which is what 9to5Google posted about.
Doesn't seem like HDMI out support is there. Will have to test with other monitors and cables to be sure, but I tested it with a Samsung monitor and USB C to HDMI cable that Google was using to demo extended display with the Pixelbook Go.
No changes to Playground AR emojis (there was a hint of new 2019 Pixel features) and no album art or activity recognition for Now Playing.
pssttt @oneplus
Since some people were wondering, yes the Pixel 4 does support DSDS like the Pixel 3a.
