I applied in-person. The process took 3 months. I interviewed at Trader Joe's (North Wales, PA) in Feb 2013
Interview
Visited the store in-person to drop off my paper application and resume. One of the managers "pre-interviewed" me and told me that he'd be in touch within 30 days, either asking me to come in for another interview or telling me that I didn't get it. I didn't hear back from the store until a few months later. I was asked to come in for a real, sit-down interview with one of the hiring managers. I already had a part-time job at this point, but I figured I could use the extra income. I went in and did the interview, was promised that I would hear back in two weeks and never heard back. It's fine it I didn't get it (for whatever reason), but I wish they wouldn't have promised to get back to me if they had no intention of doing so.
Applied online and had one in person interview with the captain. It lasted maybe 10 minutes. Got a call a week or so later that I got the job. Very fast process.
It's two to three interviews, the final with the Captain (or highest manager) of the store. The interviews are largely to get to know your personality and how well you would do at customer service.
The interview process was absolutely wonderful! I didn't feel stressed or nervous and it felt like I was just chatting with a friend! Trader Joes is a great company and the interview was great.