UPDATE: I'm posting this comment to address some of the questions you guys asked.

I'm actually an Computer Science guy stuck in the body of an Electrical Engineer. I mostly design hardware, however in my first year I did a good amount of highly optimized embedded systems programming. I wish I could go into more detail but that's against company policy.

However, my high school (the good old days) robotics mentors that also work at SpaceX are the top developers of the avionics software. What they mostly do is program the flight computer. Also the code that just brings every little sensor data together. Again I would really love to sit here and talk to you guys about the technical details, but I'm simply not allowed. So sorry for the broad sentences.

Regarding the type of people that get hired. As I said SpaceX hires the BEST. As an intern, KEN BOWERSOX, an amazing astronaut sat 2 desks away from me. I could have walked up to the guy at anytime and ask him how it was like in space. Look at this list of people running the company: http://www.spacex.com/company.php
After reading that you see how top notch these people are. The same goes for their employees.

SpaceX hires from everywhere, but it seems they are really into the stereotypical TOP engineering schools. It felt like everyone was from Stanford. A lot of people from University of Michigan, Carnegie Melon, and MIT. The company is in California, but it felt like that a huge chunk of the company was recruited from outside the state. Just go into the parking lot, and you can see license plates from every state (I saw one from Maine...long ass drive). There were few interns from the University of California system (like myself).

If you guys want to apply, I want to not just tell you all the good stuff. There is also the not so pretty side. Be prepared to give the job your everything. Specially if you are a young engineer because you mostly likely don't have any experience under your belt to make you an irreplaceable asset. Also people forget that SpaceX is a STARTUP. Yes they have 1500 employees. But this is not some little photo sharing iPhone app company (no offense guys, you really need stop with those). It's an aerospace startup, which means 1500 employees is pretty much a small amount of people. Also Elon Musk has this philosophy where a small amount of people can achieve BIG things. With that said they are hiring like crazy last time I checked (which was like 2 months ago).

Since it is a startup, job security is not good. Since the people they hire are very good, they mostly don't get fired. But at the same time the deadlines, and goals can sometimes seem like a fantasy. This sometimes leads to people getting fired. This happened a lot during my stay.

With all that said, from working at Jet Propulsion Lab, and now SpaceX my goal is turn my current graduate research into a startup. I've learned that I'm simply not the type of person that can work for others for the rest of my life. Graduating with an engineering degree and doing 9 to 5 stressful job will get old very fast. After my stay at SpaceX I already feel burned out (I worked on some high priority projects). However, I am really passionate about my current project (I can't stop thinking about it), and my goal is to turn that into a company. Unfortunately, I might have to say goodbye to SpaceX to pursue this dream.