many good recommendations so far but unbelievably nobody has yet mentioned Iain M. Banks' series of 'Culture' novels based on a humanoid society (the 'Culture') run by incredibly powerful AI's known as 'Minds'.
highly engaging books which deal with much of what a possible highly technologically advanced post singularity society might be like in terms of morality, politics, philosophy etc. they are far fetched and a lot of fun. here's the list to date:
"All you're pseudo-, pop-scientific drivel is distancing you."
immediately followed by:
""don't want to walk and talk about jesus, i just want to see his face...." Mick Jagger"
priceless.