I just need to get this off my chest. There are a lot of interviewers who will ask you trivial syntax questions, like, what does ^ mean in Ruby? Some good blog posts have made it common knowledge among better companies that these are basically stupid questions that tell you nothing about what a programmer can actually do, and don't represent vital knowledge anyway, since the answers can be found immediately on Google.
Unfortunately, a lot of companies know that these questions are trivial questions, and they know they're supposed to abandon the practice, but they don't know what they're supposed to do instead, so they just ratchet it up a notch. Instead of asking you questions which are trivial because any idiot could answer them by going on Google, they ask you questions which are trivial because any idiot could answer them by pulling Knuth off the shelf. Questions like, "what is a tree sort? What is it good for?" You can give them credit for having higher standards, because they make the hypothetical idiot go to a more sophisticated source, but they're still asking questions which any idiot could answer with access to the right reference materials. But the ability to locate reference materials isn't an important criterion in hiring programmers; it's an important criterion in hiring librarians.
Algorithm questions are becoming the huge warning sign, to me, that syntax questions were in the past. If you take a job with a company that asks you questions any idiot could answer, sooner or later they're going to put you on a project with some idiot who answered them. It's something to watch out for.
The best way to hire programmers is to read their blogs and look at their code. If you don't read their blogs and look at their code before the interview, you've gotten it backwards. The phone screen should come after the Google screen.
Even though I sometimes post embarassing things on my blog, I'm always happier in an interview when I find out the person I'm talking to has read my blog beforehand. I never talk to anybody without researching their company first, and if you googled the company but they didn't google you, that means that the first thing you find out about a prospective employer is that they're less diligent than you are. That's something to watch out for too.