I'd been looking for a game like this for a while, but found nothing searching here or Palm Gear, so I assumed it didn't exist.

Curtis Cameron, the developer of the only (that I'm aware of, but certainly most popular) Windows 42 game, has a Palm version, Palm42. With the exception of full 5-way support, it works well on my Treo.

In an email, he did say that he may further integrate the 5-way in future versions. For $15, not too bad for those looking for this game.