By the end of 2010 five billion people will own at least one mobile phone.
China has the highest number of people with mobile phones in use with 800 million users. India is second with 650 million. The USA is third with 285 million. Australia is not in the top 10.
Based on the percentage of the population who have a mobile then the top five are Hong Kong, Lithuania, Estonia, Italy, and Russia. For all of these countries about 150 percent of the population have a mobile phone—meaning every person has 1.5 mobile phones. Again, Australia does not make the top 10.
Worldwide an estimated 40 billion (40,000,000,000) SMS text messages are sent every day. That is 1,666,666,666 per hour or 27,777,777 per minute or 462,962 per second.
Primary source of data was cellphones.org (here).