Pencil v0.4.4b mac - Power PC Binary for Mac OS X 10.3.9+
Pencil v0.4.4b mac - Intel Binary for Mac OS X 10.4+
Pencil v0.4.4b windows - Binary for Windows XP, Vista
Pencil v0.4.4b ubuntu - Package for Linux Ubuntu
Pencil v0.4.3b archlinux - Package for ArchLinux

Source code - (For the latest, check the subversion repository)

Attention Windows users:
  • The movie export function has not been implemented yet (only works on the Mac). At the moment (0.4.4b) the Windows version can only export frames and Flash files. Any help would be appreciated.