Nokia recently announced the Nokia 770 Internet Tablet to be released this fall. It's a handheld device with Internet connectivity through WLAN or Bluetooth. It comes with a browser (Opera), e-mail software etc. It's not a phone, but it seems like you can do VoIP on it. Nokia wants to market it as a thin Internet client, not a PDA, but with the correct software you certainly should be able to use it as one. Perhaps it's a good alternative to a living room PC or iMac if you need something simple just for checking your e-mails or surf in the sofa.
What is interesting from a developer's point of view is that Nokia chose to run Linux on the 770. They claim it should be simple to port existing software, especially Debian applications. The framework for developing applications is called maemo.