so 25 seconds may not seem like a long time, but realistically, standing in front of someone for 25 seconds doing nothing is pretty awkward. really, try it. go up to someone and stand there counting to 25 in your head. now consider doing that in front of someone you don't really know (otherwise why would you be exchanging information?)
now consider pulling a business card out of that same pocket and handing it to the person. they can say thanks and put it in their pocket without even looking at it, then process it later.
If you could run it as a background service on the iPhone (which you can't without jailbreak), you could cut 15 seconds off that time.
Maybe given the current technical limitations it'll work better in some social settings than others. Informal ones where time isn't pressed, like hanging out with a group of people. Or at a convention. If you're sitting in a booth you could have an iPhone sitting on the table with the app open and ready to go. A passer-by might want to shoot you an email later, so they pull out their iPhone, bump yours, and away they go...
I guess thinking about it more it probably works in some situations better than others. It's niched though, and that's the stuff of entrepreneurial gold. ;)
You'll probably be able to cut that time down if you don't use a pin code (I don't), and if you put the app in the bottom row of apps.
If you go back to the days when Palm Pilots were the rage, you could beam your business card over the IR port on them. People still used biz cards, but two people who had a Palm didn't.
I'm probably a bit bias as I live in a city (Boston) that's littered with iPhones. Lots of people have them, including my friends. There is a mini-technology gap between people who have them and those who don't. If you're in the "iPhone crowd" something like this seems really cool. Otherwise, meh.
If this suddenly worked on every cell phone in the world tomorrow, not just iPhone's, you'd probably have a lot more people interested in it.
1) You've got to design and pay to print them. If titles or contact info changes, that's a re-print. The cost matters a lot particularly to the SoHo market.
2) You've got to carry them around with you everywhere to hand out. Usually this is in a metal case that's kinda cumbersome in a pocket shared with an iPhone/BlackBerry already.
3) When someone hands you one, you've gotta stick it in your pocket and not lose it.
4) After you bring them to your office, you need to file them somehow (scan them, manually enter them into Outlook/whatever).
I've seen people at hedge funds buy expensive scanners which plug into Outlook and let you scan this stuff in. It does OCR on the cards and auto-creates contacts for you. The scanners are around $200/each, plug into your desktop, and are a tad annoying to install and config. The cards get tossed into the trash the moment it's in Outlook.
If you don't buy a scanner for every employee, that's time wasted while they type said card info into Outlook.
While something like this won't "kill" business cards in the business world, it'll offer a nice alternative.
Here's an idea for an iPhone App that'll let someone with an iPhone do-away with biz cards all together: A scanner app using the iPhone camera. Take a snapshot* of someone's biz card, OCR it, and bam, it's in your contacts. Easier said than done, of course. But it eliminates steps 3 and 4 above, making your life easier when dealing with "legacy" business cards. :)
*Yeah, yeah, we all know how good the iPhone camera is at close-ups. Maybe the next revision? ;)