I would say internships can definitely be helpful, even if they don't lead to a job at the company where you're interning. Ed. Assistants don't necessarily have to have publishing experience, but it helps. I think the most important factor is a demonstrated interest in books and writing as well as a proficiency at general administrative tasks, communication, and organization. When I got hired on as an EA I'd been an intern at Conari, a volunteer/intern at Small Press Distribution, and a customer service rep at Chronicle, in addition to a temp and random other administrative jobs in other industries.

Subscribe to Mariah's wonderful SF pub group on Yahoo groups (I'm assuming you're in the bay area: groups.yahoo.com/), that has good job listings, and also check out Craig's List under editorial/writing jobs. That's where I found my current job as an editor. I don't know if there's another editor job/internship database anywhere.

In my experience, finding good editorial assistant help is hard, so if you have a solid administrative/organizational/project management background, if you communicate well, and if you can show that you want to make publishing your career, that should really help.

In my experience, editors shy away from people they think expect the job to be glamorous and exciting. In all the interviews I've had for EA jobs, the editors can't stop repeating the mantra "Now, you won't be doing much editorial work in this job, it'll mostly be administrative tasks." So be open to that, and expect to be an EA from 2-4 years before you advance.

Unfortunately, there's a lot of competition for those jobs, so that's just something you'll have to deal with. A history of book-related employment, volunteer work, or even hobbies can help you stand out.

Really glowing letters of recommendation stressing your administrative, organizational, communication, and project management skills, in addition to a professional, well-put-together resume are also good. You'd be surprised at how many resumes I've seen just tossed in the trash because the applicant misspelled something in their resume or cover letter, or the resume and letter were handwritten or badly typed or photocopied, or the person seemed to just want "a job, any job".

I think I went on 15 interviews before I got my first EA job. It's tough, but definitely worth it.

Good luck!