If 75 days = 500 generations, then this experiment has been going on for over 20.5 years. Wow. This is spectacular.
E. coli are a wonderful model system because their generation time is so short that it allows us to observe evolution in action. From this we can make inferences about how evolution works in longer-lived species.
Some people choose not to accept observations, however. View the dialogue between Dr. Lenski and Mr. Schlafly. I think Dr. Lenski states the case for responding to creationists well:
"I offer this lengthy reply because I am an educator as well as a scientist. It is my sincere hope that some readers might learn something from this exchange, even if you do not."
At my poster presentation to the public (at the Graduate Exhibition), I am fairly confident one of my judges was a bigoted creationist, and another asked me, "How do you respond to creationists who approach you about your work?" My response, fitting after the previous judge, was that if someone approaches me, with ideas that are not founded in anything but their own desire to desperately believe them, there's not really any evidence I can provide that will convince her or him otherwise. It may be a side-step, but I try to focus on parts of the science where I can find common ground, if said person is honestly interested in the research, but find that it is not only useless, but counter-productive to try to teach the basic concepts of molecular evolution in a 5-minute conversation.
One of my favorite quotations was shared by my uncle with me:
"You can't reason out what wasn't reasoned in."
So, rock on E. coli, rock on.