I'll respond to both of the two posters above here.
To the first poster, you don't honestly need to make contacts per se in NYC before OCIP. The beautiful thing about applying to NYC firms is that it is one of the few locations (possibly the only location) where you don't need any ties to the region justifying your application. It's pretty widely accepted that NYC interviewers think that everyone wants to be in NYC, and thus they don't question your ties. That being said, reaching out to alums *never* hurts, and I would recommend doing this before you interview. All you have to do is send a few emails to some Boalt grads before OCIP and let them know that you're really interested in the firm, will be interviewing with them during OCIP, and would like some info. I've found that most (if not all) alums I reached out to were happy to call and chat with me for about 30 mins or so about the firm. Then when I walked into the interview, I had some inside knowledge - I was able to say "I am really excited about your firm - I chatted with so-and-so, and she told me all about X." It's likely that your interviewer will reach out to whoever you talked to, and that person will put in a good word for you as a fellow Boaltie. (To find Boalt alums, go to a firm's website, click on a tab for "lawyers" or "who works here" or something like that, and then filter by school.)
Another thing: some firms in NYC would love to have Berkeley kids, but don't have the budget to fly out to CA to just visit two schools (you know the other school I am taking about
). On b-Line, which is our job site, there are a good number of big law firms from the East Coast that solicit resumes and then will fly you out for an interview. Don't discount this process. These firms usually start posting resume solicitations as early as June before OCIP, and as late as the Feb or March after OCIP. One that comes to mind is Fried Frank in NYC. I applied to them through b-Line and landed a callback style interview before OCIP even started.
Last bit of advice: be proactive. Don't sit around and wait for the firms to come to you - go to them. There will be a list on the career site that shows every firm that came the year prior. Until your year's list is posted, use this old list. I guarantee not much will have changed. Send resumes over the summer (like, starting in June), to all of the firms on the Vault list that don't come to Berkeley and don't solicit on b-Line (don't bother sending apps to firms that come to campus). Let them know you're interested and will be in town (if you will be, of course!). There are about 100 firms on the Vault list, and there are a bunch that don't come and don't solicit resumes. If you're deadset on NYC, send as many apps as possible to increase your chances.
Last last bit of advice: if a firm has a NYC office but doesn't send a rep from that office, you just interview with whoever is there (let's say, SF or LA) and let them know you're interviewing for NYC. But this will all be explained much much later when you start going through the OCIP info sessions.
To the second poster - A lot of what I said above should help you out. But yes - my general understanding is that Bay Area (I'm including Silicon Valley) and even LA firms favor Boalt over NYU. But this might just be because Boalties tend to stay in CA and NYU'ers tend to stay in NY, and as a result, there are more Boalties than NYU'ers applying for jobs out here. I know that almost all of the top firms recruit here - they fly out for OCIP and send representatives and host hospitality suites, sponsor cocktail hours, etc. An exclusively East Coast (NY and DC) firm just sponsored a law review retreat even though all of us have our jobs already. I think employers in NY do tend to see Berkeley kids as "exotic," and they know it's a good school.
I can't speak to the portability of a NYU degree, but it's also a great choice. My boss at my current internship (fed gov't, rather not say where) is an NYU law alum working in SF. Basically they are both really good schools, and having a degree from either will open doors for you. If you want to be on the East Coast and you're from Boalt, there are options. If you want to be on the West Coast and you're from NYU, there are also options. I don't think going to school in NYC or SF will limit your future career opportunities to those cities alone.