The Agora Project seems like an interesting idea for a library.
dpope from the Compiz.net forums explains that:
Several people expressed interest in working on a library that would package opengl graphics/animation in a useful way so that this functionality can be cleanly and easily integrated into windowing libraries such as gtk or qt.
Quinnstorm later suggested:
[W]hat if agora was the frameworks, and CoDE was the actual desktop environment?
To which MacSlow replied:
Sure, that's the main idea behind "Agora". Be a framework or library (libraries) pulling together the nice low-level bits like OpenGL, cairo, gstreamer & Co and offer a solid set of ready to use animations, effects and filters for everything put on the screen. Kind of the Xgl/compiz on the application- and toolkit-level of things.
What you want to build with it afterwards... the next gtk+, Qt or desktop-environment is up to you.
It looks like this might the Linux community's answer to Apple's CoreImage and new CoreAnimation APIs (and probably others as well). It'll allow application programmers to add a little more bling to their apps. However, don't get too excited yet - Whatever the Agora Project ends up becoming, it's certainly at least a year off. Building a library that melds together several APIs requires a deep understanding of each of those APIs, which is not something tha comes easily. However, if the project attracts good talent like MacSlow (who's made a name for himself by creating some pretty cool apps), it certainly won't be an impossible feat. We'll see where this one goes. :)
If you'd like to follow or contribute to the development, check out the Agora Project forum that has been set up.