You could request a free unlocked Palm Pre2 at:
devmarketing@palm.com
From Palm Developers blog:
http://developer.palm.com/blog
"Creating Mojo apps for exciting, all-new HP smartphones
Press and users alike are excited about the all-new Veer and Pre 3. The great news is that these new smartphones come with webOS 2.x, which support apps created in Mojo. These phones provide a huge opportunity for you to update and deliver apps for all-new webOS devices people will want and love for a long time.
To help out, we are extending our free Pre 2 program to all qualified developers. Contact us at
devmarketing@palm.com to see how you can receive the latest device to test your apps."
It is very easy to take for example the C source code available for the Nokia N900 make it run in the Pre/Pre2. The integration with the UI would be specific for WebOS but it is very easy and there are very good examples and help available in the homebrew community.
http://www.webos-internals.org