Opera Watch has a informative post about whether we will ever see the Opera Mobile browser for the Palm OS. Basically it boils down to the fact that there is insufficient interest from Palm itself. While the newer Palm browsers are workable alternatives and Opera Mini is full of issues when running on the Palm OS, it would be nice too see Opera develop a browser for the Palm OS, breathing much needed innovation into the marketplace.
Update: 5.31.06. There has been some confusion about Opera Mini and Opera Mobile. They are different products. To see a good example of the difference look at Opera for Windows Mobile Pocket PC.