One of the world’s most populous countries is leading the way as the mobile revolution continues to saturate the globe with mobile devices: India. A recent study by the market research firm Juxt polled an extraordinary number of respondents – 121,311 individuals in 30,066 households across India – and found that the nation now can claim roughly 554.8 million mobile users!

That’s right, there are more mobile users in India than there are people in the United States. And what’s amazing is that this figure was only half as large a few short years ago.

According to the study, these users employ 643.4 million active SIM cards, and there are approximately 773.9 million live SIMs in India. Of these users, 23.8 million individuals access the Internet through a mobile data connection such as GPRS or 3G. More interestingly, a million of those users connect to the Internet exclusively via mobile.

No desktop. No laptop. Just portable, mobile Internet accessed through a handheld device.

The great age of the keyboard and mouse has peaked and is now declining. The new age of touchscreens and miniaturized predictive typing is on the rise, and India is demonstrating the trends quite clearly.

What might surprise you, though, is that a majority of the users who access Internet exclusively through mobile data connections are in rural areas. You might not associate rural communities with being technologically progressive, but in this case, we’re guessing that mobile connections provide convenient access in locations where obtaining a reliable hardwired home connection is difficult. [Commenters, if you’re familiar with the reasons behind these stats, we’d love to hear more!]

Indeed, a slim majority 54% of India’s mobile users live in rural areas. And yet mobile saturation is only at 36% (urban mobile saturation is far more developed, as you might expect, having reached 70%). This means that opportunities for growth among rural mobile users in India are quite robust. For small businesses in India and app developers, the message is clear: the always-growing mobile space is practically begging for increased attention, and rural users should be at the center of your efforts.

What do they want? Well, according to the study, landline users are focused on games, videos, and music, but mobile users are all about communication. Thus, social networking, instant messaging, and e-mail are the favorites of the mobile user. Keeping in touch, it seems, is the most useful feature of mobile devices. And users are keeping in touch more than ever.

The numbers don’t lie. If you ignore mobile, you do so at your peril. The users can’t get enough of it, and if your business focuses on mobile, they won’t be able to get enough of you, either!