I saw the Android demo just a few minutes ago and was highly impressed. They're definitely taking a lot of Apple's UI ideas from the iPhone. (And rightly so, since they're good ones.) But unfortunately I don't think an Android-based device is going to replace my N800 anytime in the near future. I chose the N800 over the iPhone (or iPod touch, anyway) for two big reasons:

1) The hardware is vastly superior (bluetooth, memory cards, speakers!) yet less expensive.

2) The iPhone OS, middleware, and applications are entirely proprietary. The NIT software, on the other hand, is almost entirely open source and I like supporting open source companies as much as having devices which run open source software.

When I went to download the Android SDK from the official website to tinker around with it, I found that it has a very restrictive, proprietary license. A bit of quick searching confirmed that while they're offering repository access to the open source bits that they use, Android as a whole is completely locked up just as tightly as the iPhone is.

I'm rather anxious to see what the OpenMoko folks will come up with (if they ever ship a product) but for now, the NIT seems to be the most open-source-friendly device on the market.