http://www.applematters.com/article/october-20-1997-last-newton-introduced/
For those still addicted to the Newton the most desirable model is the Message Pad 2100. The handheld (not pocketable) PDA was leaps ahead of most other Newtons. It features support for an Ethernet card (a first). Users also loved the expanded memory of the 2100.
The fact that the Newton 2100 was even released is more interesting. Steve Jobs was back at the helm and efforts to spin the Newton off as a different company had been quashed. Turns out that the 2100 was already complete and the release was just a way to recoup some of Apple's investment.
Apple's last Newton was introduced on October 20, 1997.