Simple 2D Animation Software for UNIX-like OSes

BSDanimation asks: "I want to create slide based cartoon-like animations with speech bubbles and simple programmable 2D effects in a widely accepted format like MPEG or AVI. I have considered using Ming to code a Flash animation, but then decided against Flash and would prefer to stay away from such proprietary formats. Blender seems nice, but is too complex and a complete overkill. OpenOffice presentations seem promising, but I am not sure if it is possible to program effects and speech bubbles in it and export such presentations into a format other than Flash. What free UNIX-like OS based open source software is there for such simple 2D animation that would also allow me to distribute my animations commercially without any licensing restrictions?"