LÖVE

I'm currently drawing parts of my scene into framebuffers, and then drawing those framebuffers into the scene. I can't figure out a way to get anti-aliasing when drawing into these framebuffers, though. When I draw the framebuffers onto the scene, their contents are quite jaggy. I've got FSAA enabled on the game, and using love.graphics.setMode when a framebuffer is bound freaks the game out. What am I missing?

There could be one of two things happening here: your framebuffer isn't being anti-aliased as much as you want, or it's the victim of a lack of premultiplied alpha blending. Framebuffers drawn to the screen with alpha blending will only look proper with the "premultiplied" blend mode instead, however it's only available in LÖVE 0.8.0. For alternative anti-aliasing solutions, you could look into things such as FXAA and SMAA, however they're probably not exactly what you're looking for.