According to The Android Guys, "You can get a sense for how the phone notifications work, like new SMS or incoming calls. You can also play with the menu, checkout the e-mail setup, and add shortcuts to desktop. Also on the same page are demos to show basic things like SIM, battery, and memory card insertion. Oh yeah, there's a fully rotatable look at the G1."
Since I've already had a chance to play with the G1 for a while, I know what I'm missing in not being able to use the emulator. Not all of the G1's feature work within the emulator, but for those who haven't had a chance to take one for a test drive, this is the next-best thing...until Oct. 22.
In case you can't get the emulator to work, either, here is a video of the Android user interface: