By Caroline Waxler, contributor

One of the first pieces of advice given to anyone who goes to the South by Southwest interactive conference in Austin is bring enough business cards. And don’t be surprised when you run out.

Not this year.

At the 2010 conference, exchanging physical cards (remember those little rectangular things?) has become analog to using last year’s anything. Instead, people are going paperless, mostly “Bumping.” That is, using the iPhone application Bump in a kind of fist-bump move (with an iPhone or Google Android in hand) to exchange contact information.

From there your mobile network provider reports in the exchange to Bump HQ whose algorithms are looking at every Bump to match the two phones which Bumped at the same time in the same location. It also lets you instantaneously to send a Facebook Friend request, if you want.

Bump launched last March and has now had over ten million downloads. At the conference to promote the app, Bump cofounder Jake Mintz, says he doesn’t have any Austin-specfic data available, but that tens of thousands of Bumps have taken place worldwide since the conference began.  Click here for a Bump-tracker  (and here for Foursquare and Gowalla check-ins).

“I’ve met just as many people as in past years, but have exchanged much fewer cards,” says Maya Baratz, product manager at MTV. “My pile has waned significantly.” (I, myself, gave out a fraction of the cards I brought.)

“I remember contemplating purchasing a business card scanner a few years ago because I’d get so many cards at conferences. I’d say of the hundreds of cards you can collect, only ten or fifteen I actually enter into my computer contacts,” says media blogger Irene McGee of No One’s Listening.

Says Pandora CTO Tom Conrad, “”When I need a business card, they’re almost always at work in a desk drawer. On the other hand, I always have my iPhone, so with Bump I can instantly share my contact info or find a common friend.”

Bump is far from the only player in its virtual space. The South by Southwest organizers, for example, put a quick response code technology on attendees’ badges that can be scanned if you have the right device on your phone. Once scanned it connects you to your page on the SXSW site. “It’s another way to foster community,” says SXSW producer O’Keefe. For a community that likes to geek out, what could be geekier than that?

But not everyone is getting into it. “Just like no one pokes me on Facebook, no one has offered to bump me, but that is more of a reflection of me,” says Jacob Lewis, founder of Figment, a mobile platform for reading and writing young adult fiction. Indeed, it may be used as a cutesy way to talk to strangers. “There are some people who play up the sexual innuendos,” says Bump’s Mintz.  “It can be fun. Someone came up to me last night and said, ‘I’ll never forget the first time I was Bumped.’”
The money guys at this conference aren’t big on Bumping. “I’m on a Blackberry so I can’t Bump,” says Simi Blaustein, IAC’s director of strategic planning and M&A, who instead gave me his card. (Bump’s Mintz says he is working on Blackberry but doesn’t have an estimated release date.)

Richard Moross, CEO of Moo.com, which lets users take images to make business cards, says that he has actually seen an uptick in business this year. “Some of the emerging virtual business card ideas are great, but they universally lack one critical ingredient: personality. Form is still just as important as function these days. A virtual business card is just data.” Moross hinted that his company may be figuring out a way to make the virtual business card space much better looking.

Trends at SXSW tend to spread. Many great technologies start out as toys, which people initially dismiss to later embrace. Bump could well fall into that camp. And people have been calling for the end of business cards for the last ten years, but now finally feels like the right time. Or close to now.

“As far as the digital data exchanges here at SXSW, almost all of the Bumps I witnessed experienced total technology fails and ended with the people resorting to the old analog method,” says influential blogger Cathy Brooks of Other Than That.

Indeed, phone networks have issues that can derail the process just as phone calls can get dropped. So what did I resort to when my iPhone wasn’t working and my contacts didn’t have business cards? The very, very retro pen and paper.