When Palm first showed the Pre in January during the Consumer Electronics Show in Las Vegas, they stated that the device would hit the shops in the first half of 2009. They barely made this deadline, but a casualty of meeting this deadline was the SDK, which was not ready for release alongside the Pre itself. Instead, Palm promised the SDK for this summer.
Well, if you want to, you can already play with the SDK now. A limited access program is under way, and for some reason, Twitter user @robovalzuniga posted a download link. Obviously, the SDK is in beta, and Palm doesn't want it to be out yet. They haven't contacted any of the sites reporting on this one just yet (it's the weekend, after all), but there's of course also the remote possibility that the SDK isn't leaked, but that is has been "leaked". Pure speculation, though, obviously.
And the fact of the matter is - Palm can use the SDK. The application catalogue for the Pre is quite small (they hit the 1 million apps downloaded, though), so Palm could use a number of new applications. The demand is so high, in fact, that Pre tinkerers have already found out an incredibly easy way to get new applications on the device - without even having to root it.
The SDK comes with a webOS emulator, so it could also be fun for those of us without interests as a developer. The leaked file is Windows-only.