An iPad or other similar digital device is of good use in this case.  Pre-load your website, animations, etc., and you are done.  Best part is that everything looks like it did on the screen with zero adjustments for print, and the interviewer can play Angry Birds if they get bored with you.  You just better hope your interface is intuitive, your labeling is right, and that you can explain things without having to sit right next to the interviewer; It's too difficult to look someone in the eye and ask them a question when that close.

If the iPad wont work, get to printing.

Not if you've already given them the link to the website during the application process. I've been very disappointed when I brought in candidates only to have them walk me through a website that I've already taken the time to view. The interview should be an opportunity to go through your best work more in-depth, so you should be bringing them something they haven't already seen before, supplementing the previous viewing somehow. So if all you sent previously was a few pages of pdf and no web link, then web miggght be ok, but if they've already seen the site, at least bring in a roll of drawings, something to make them feel like they're seeing/learning something new about your work.

i'm going to be helpful here:

have both.

keep the most up to date version on your tablet. everyone should have a tablet at this point. it more than pays for itself if you actually spend time reading, like every non-shitty human being should.

you can't predict the format of an interview in this profession. some interviewers will go all out corporate and avoid any personal questions, while sitting 5 feet away from you in a conference table. others will sit next to you and try to find out if you know anyone they know and figure out how you're connected (you should be. otherwise, get out more). the latter are your target audience for a digital portfolio

you should always keep a paper version of your portfolio for those interviewers that will sit across from you. assume the dude across from you is too dumb to slide through acrobat slides on an ipad.

..Anyways... a website portfolio should be about archiving your most recent work and learning new tech. unless you're doing business with actual clients and not looking for a job, most people doing the whole hiring thing are old/computer illiterate and don't know shit about how to run themselves through issuu/archinect/carbonmade/behance/cargo in search of good candidates. hopefully that will change. but for now, cater to the luddites. bring a paper portfolio. assess the situation. react accordingly.

Bring 4 iPads. And a hard cover printout of the portfolio (make it 4 of those as well)

Last thing you want to do is come across like you actually need the job. That would be just plain vulgar.

I find it absurd if you don't bring a small projector with you. Every office is painted white on the interior specifically for this reason. You only bring a tablet for the most senior partner interviewing to use and you should let him keep it when you leave. Everyone else gets a paper version or an iPhone with your portfolio loaded on it.