I was contacted by a recruiter and only had my phone interview 2 weeks later. I had to reschedule my interview, because they flaked on the first. The low life recruiters they hired there are very unresponsive and impossible to get a hold of.
First off, if you were contacted by the recruiter like I was, this is called fishing. These guys are fishing for the brightest minds in the country. Be prepared to answer some impossible questions. My uncle is a senior software engineer at Oracle, and even he laughed at some of the questions that were posted here on this website as interview questions. Basically, don't feel bad if don't pass the interview process. Amazon.com isn't what its cracked up to be. Besides, if you somehow squeak by the interviews and get hired, are you really going to be happy competing with Joe Blow, who codes for fun at home?
Get a life JOE!
Okay on to the questions:
These guys love the following topics: Binary Trees and Binary Search Trees, Searching Algorithms (Quick, Bubble, Merge, etc...), Hash Tables, Strings, and Algorithm Complexity. Know the differences between Java and C++. If you know the following topics inside and out, you should be golden. Just don't tell them your a crazy psychopath looking for your next victim and you should get that cube next to Joe. =)
Good luck.
If you haven't already looked for jobs at Intel, I suggest you do. Believe it or not, Intel does software too. I did an internship there over the summer. Awesome place to work. They don't put you through the ringer like these communists at Amazon.com do.