But despite the growing popularity of check-in services in the U.S., there are still many who are reticent to share information about their geographic location. According to The Nielsen Company’s latest research on mobile applications, most mobile app downloaders, which Nielsen defines as those mobile subscribers who have downloaded an application in the past 30 days, are concerned about privacy when it comes to sharing their location via mobile phone. This concern is more pronounced among women app downloaders, with 59 percent reporting they have privacy concerns compared to 52 percent of male app downloaders.

Age is a factor as well. Mobile app downloaders between the ages of 25-34 were the least likely to have privacy concerns. Privacy concerns were considerably higher among those over the age of 45.

As consumers become increasingly familiar with location-based apps, and as marketers earn their trust and become more savvy about understanding what benefits consumers expect in exchange for that information, consumers will become more comfortable with the idea of location-based mobile applications.

Jonathan Carson, CEO, Telecom, at The Nielsen Company, will be sharing these and other insights on consumers and mobile apps at the upcoming AppNation conference in San Francisco on April 27.

In contrast, John McCain’s campaign has largely eschewed mobile marketing.  But that may just be the right strategy, according to Nielsen Mobile, which reported Monday that mobile advertising is a more efficient way to reach Democrats, rather than Republicans.

As of the second quarter of 2008, mobile media of all types were slightly more popular among Democrats, who were more likely than their Republican counterparts to use data services on their mobile phones, send text messages, or use mobile Internet, according to Nielsen.

View the full media alert.

Read coverage of Nielsen’s findings in MediaPost, Wireless and Mobile News, and Fierce Mobile Content.