the meaning of "Where are you going with this?"

Yes, it's similar to "what are you getting at?"

It's another way of saying, "what's your point?"

You can use it in the same context as these other locutions.

It does seem to convey a certain defensiveness about it, though, as, for example, a response to interrrogation or accusation.

Thanks

I agree, but it can also be used in a sarcastic way, insinuating, by asking that question, that the one being questioned is rambling in some incoherent way.

You might say "where are you going with this?" if you suspect you know where the other person is "going", but for various reasons you want them to say it themselves.

"Yes, and?" does the same thing.

"What are you driving at?" is another way of saying it.
And, "What do you mean?"

E.g.
Son: Dad...
Dad: Yes?
Son: You know you don't like use the car like in the week?
Dad: That's right.
Son: ... and you know my college is like five miles away?
Dad: Yessss....
Son: ... and like chicks think guys who use the bus are like lamers?
Dad: Where are you going with this?

Thanks for your responses! Now I understand the sentence completely ;-)