It has been announced recently that Anthony Flack is hard at work on his upcoming action-platformer Cletus Clay, which has been in development for several years now. Much like Platypus, all objects, backgrounds and sprites are made out of clay and animated using traditional stop-frame techniques (e.g. The Neverhood).

No mentions of any release dates yet.

Cletus Clay blog live on TunaSnax
message from Anthony Flack
The Making of Platypus (Squashy Software)