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:

• Consider Phlebas (1987)
• The Player of Games (1988)
• Use of Weapons (1990)
• Excession (1996)
• Inversions (1998)
• Look to Windward (2000)
• Matter (2008)

they are not consecutive so reading order isn't that important though it is nice to follow their evolution from the perspective of the writing.