Now, that philosophy, in the wrong hands, can go really bad. You can start to pimp out your church for various famous people, and start to mis-prioritize things to try to have vaguely defined "cultural influence". disclaimer taken to heart. . . . .
But, I don't think Tim Keller is the "wrong hands" (I'm a calvinist). He puts out great stuff (always really, deeply helpful), is a ridiculously smart, pastoral, defender of the faith, and he's pastoring some influential people as well.
Here's two interviews he did recently about his new book (which looks really great and insightful); ironically, both of the interviewers on national t.v. networks, go to his church :). He defends the faith so winsomely and wisely. What a great spokesman for our faith! Let's keep him in prayer. (notice the yoda-like way he engages the Rabbi on the MSNBC clip)
Here's a Q and A he did with Brian Chappell where he gets really detailed on how he applies the "cultural influence" stuff and shares alot of personal wisdom as well. If you want to get to know Tim Keller a bit. . these are great Q and A sessions. He also talks about how a higher-up MTV exec went to Redeemer, and how he counseled him through some tough decisions.