I’m now the proud owner of a Palm Pre and I’m looking forward to being able to possibly develop some Apps for it.
The SDK for the Palm Pre is currently in pre-release and early access form only. There is also a huge NDA to go along with it.
The SDK makes use of Java, Safari (for debugging), and VirtualBox (for emulation) on Windows.
You can sign up for early access to the SDK at the Palm Developer site. There you can also read the first chapter of the developer’s guide for developing with the Mojo SDK.