I applied online. The process took 2 months. I interviewed at Zynga (San Francisco, CA) in Sep 2010
Interview
Pretty straight forward process. Had a brief phone interview with a recruiter then after a week or two I was asked to come in and meet with 4 people.
The face to face interviews were pretty straight forward, laced with bunch of standard interview questions in relation to my background/experience and some personal. Everyone was pretty nice and I never felt uncomfortable. The manager did look stressed and did make it a point to let me know how busy and undermanned they are being a start-up and all. Overall, the process was pretty straight forward and basic.
The only thing I didn't appreciate was that I never got a follow up. I was told that the recruiter would keep me posted but after not hearing from them for about 2 weeks, I sent a follow up email which they did respond to saying they are still in the interviewing process and would get back to me once they make a decision however I never heard back from them.
I applied through an employee referral. The process took 2 months. I interviewed at Zynga (San Francisco, CA) in Apr 2011
Interview
My friend who interned for them last summer referred me to a Zynga employee because of my iPhone development skills. A person from HR promptly contacted me and asked to do a phone screening. In 2 weeks I talked to an HR who asked basic questions and simple knowledge questions like "Are you familiar with vectors, what are the most important concepts in programming, etc".
He then said he would get back to me. 1-2 months later I sent a follow up email (you probably shouldn't wait that long) and he was happy to move me along the interview process (it seems he forgot. and after speaking with my friend who interned there as well, this is common. Being a startup I assume things get pretty hectic so you should stay on them). I was then scheduled 3 phone tech interviews for the following week. The questions mainly involved PHP/MySQL questions, and some related to multi-threaded programming. The intervieweres were extremely nice and were willing to give you 'hints'
I got a call in 3 business days from HR saying that I got the internship.