Joel Spolsky argues recently somewhat tongue in cheek that Java just isn’t a good language to differentiate potential programmer candidates. At a high level I can agree with the sentiment that you want to know that someone knows more than Java.
On the idea of weeding people out I can’t say that his focus on understanding the ins and outs of pointers makes a whole heck of a lot of sense. Doing my undergrad at Georgia Tech in Physics many years ago my weed out courses were Differential Equations and Thermodynamics as I remember. I remember a time honored tradition at Tech was explaining to the incoming freshmen:
Look to your right, now look to your left. By the time you graduate neither of those people will be there.
I remember thinking at the time that they were exaggerating. By the time I graduated 4 years later I realized they weren’t.
Still with most candidates I look at the college they graduated from is a single line on the resume. Much more important is what they’ve actually done and whether they can actually describe it. A really great candidate would have a blog they could point me at and maybe an open source project or two that they had contributed to. I’m not sure that having them explain pointers means much to me, but I do typically ask a question about which language they’d prefer to use and why?