Starbucks is the latest company to use mobile marketing to engage its customers in creative ways. The Seattle-based coffee giant just unveiled two new iPhone apps. The first one helps you find the closest Starbucks and search calorie and ingredient information for drinks. But the second one is what is getting so much attention.

The Starbucks Card Mobile app isn’t just an easy way to refill your Starbucks card, though it does that as well. What’s really exciting about the app is that in two experimental markets (Seattle and Silicon Valley), the app will use a barcode to replace the plastic gift card.

Why does this matter? CNET’s Caroline McCarthy explains it best… mobile marketing customer engagement programs, from text message promotions to mobile bar codes, hasn’t quite caught on in the US, even though they’re huge in countries like Japan and South Korea. “Having a unbiquitious national retailer like Starbucks in the game could change this,” writes McCarthy.

The Starbucks card app is a test only, and Starbucks isn’t sure when it will be able to roll it out to other markets, if ever. It all comes down to whether the time is ripe for mobile barcode technology in the US. That time is certainly coming close, if it isn’t here already.

“Increasingly consumers are centered around their phones, and more of the functions of the wallet are migrating there,” said Ross Rubin an analyst for the NPD Group, in the New York Times writeup on the Starbucks apps. Rubin noted that technologies like mobile bar codes and near-field communication will likely make mobile transactions a reality in the US, though when they will take off is still unclear.