It usually takes me about 60-90 seconds to eat a cupcake; this guy took about 10 minutes with his. On view: the new camcorder function, soft keyboard, browser improvements and YouTube uploads.
As you can see, it's not final final yet, as the video recording is still a bit buggy, but overall the improvements look nice.
This is an official development build issued by HTC yesterday we're seeing. It's for dev phones only, technically, but if you have a rooted G1 you can install this just like any other "update.zip" recovery image. See our how-to guide as well as this XDA developers thread for more guidance on upgrading your G1 if you so dare. We're still looking at a non-specific May release date for the official OTA update.