I would recommend you watch the latest episode of the Linux Action show. They mourn Nokia's betrayal of the open source community but also offer several alternative options for open mobile development. http://www.jupiterbroadcasting.com/?p=5232

Here are some links from their show notes.

Linux Cell Phone Distros:

Maemo – http://maemo.org/
Hildon – http://live.gnome.org/Hildon
Mer – http://wiki.maemo.org/Mer
MeeGo – http://en.wikipedia.org/wiki/MeeGo
OpenMoko – http://wiki.openmoko.org/wiki/Main_Page
Qtopia / QT Extended – http://en.wikipedia.org/wiki/Qtopia
OPIE – http://en.wikipedia.org/wiki/OPIE_user_interface
SHR – http://shr-project.org/trac