I have just finished Tim Keller's sermon on The Gospel and Idolatry which he gave at the recent 2009 Gospel Coalition conference, and it was indeed a good sermon. Keller exegeted the text well and expounded it for our benefits, and it would do us good to examine our lives to see if there are indeed any idols we still harbour in our hearts.
[As it can be seen, I give credit when credit is due. Just because Keller compromised the Gospel in the area of Creation and Apologetics does not mean he is the Devil incarnate. I also respect him more than the other prominent New Calvinist pastor, Mark Driscoll. At least Keller is biblical here and exegeted the text he based his sermon on.]