Market researcher comScore says its cross-media panel of PC and mobile Internet users in the U.S., found that light PC Internet users are 30 percent more likely than heavy PC Internet users to use their mobile devices to access Internet content.

In total, 42 million people used their mobile devices in October 2008 to access news and information content on the Internet. That’s an increase of 57 percent from October 2007, says comScore.

The study found that 15.2 percent of light PC Internet users accessed news and information on their mobile device at least once per week, compared to a lower 11.7 percent of heavy PC Internet users. The study also found that mobile Internet users are more likely to be male (58 percent) and to be 18 to 44 years of age. Light mobile Internet users are heavier users of the PC.

ComScore defined “heavy” PC Internet users as those who viewed, on average, 6,701 pages in the month, and “light” users as those who viewed, on average, 1,104 pages in the month. Twenty percent of PC Internet users in the cross-media panel were classified as heavy users, and accounted for 43 percent of overall page views, while 50 percent were light users and accounted for 18 percent of page views. The balance was classified as medium users.

The study was conducted using a sample of individuals who were members of comScore’s PC panel of online users and who were also participants in comScore’s monthly mobile survey. The findings above represent digital media usage for the three-month average ending October 2008.

According to IDC’s Worldwide Mobile Phone Tracker report, the smartphone market grew 22.5% in 2008 while the mobile phone market declined 12.6% in 4Q 2008. Smartphones are currently about 15 percent of the entire mobile phone market, but are predicted to grow to 40 to 50 percent within the next five years. Informa forecasts subscriptions to UMTS/HSPA will number nearly half a billion worldwide by the end of 2009, and will pass the one billion mark in 2012.

Mobile Data Traffic by Application is expected to shift to video and internet access.

Total US Internet ad spending will increase to $25.7 billion in 2009, says eMarketer, an 8.9% growth rate. That will be the lowest year-over-year increase for online advertising ever. Yet it will still be a robust increase compared with nearly all other media.