Why is there still no true 770 competitor?

I think there are a lot of people that still don't "get it". I won't go back into that unwieldy discussion about how the 770 is or isn't like a UMPC, but I think it's safe to say that the Internet Tablet is very much a mobile Linux computer. Sure, it doesn't have a keyboard like many other similar mobile devices, but it does have a couple of realistic options for text input.

How are you gonna use that keyboard while standing or walking for example?
The full screen "thumb" virtual keyboard is perfect for situations like this.

And wouldn't you rather have a full sized keyboard for typing anything longer than a quick text message anyway?
That's where the USB and Bluetooth features shine. Connect to a "normal" sized keyboards for tasks that require them.

I think this is also one of the reasons Nokia was able to keep the cost of the device so low.

Secondly, mobile Linux devices are still fairly uncharted territory, and previous attempts have been either "half-baked" or just didn't gain the momentum needed to sustain growth of the given platform. In either case, manufacturers dropped support at the first sign of stagnancy.

I also think the time is just right for mobile Linux as competitors like Palm, Toshiba, Sony, HP, and others have moved out of the mobile computing landscape or just haven't moved at all.