He's all super duper extrasecretive about what they've got cooking, but Palm founder and CTO Jeff Hawkins reveals in an interview with the San Jose Business Journal that Palm has a third business (after PDAs and smartphones) that they haven't yet revealed to the public. He does mention that it has something to do with mobile computing, but that'd be like McDonalds revealing that they've got a top secret project related to food:
There is a third business that I've been working on but I'm not going to tell you what it is. It's in mobile computing. It's something different and it's in its early stage. We have three businesses at PalmOne. One you don't even know about, which is just a child. Another is the teenager and the other one is the mature 45-year-old.
Q: Can you give me a better idea about what this "child" technology is?