????By Philip Elmer-DeWitt

????Owners of Apple (AAPL) iPhones who hold down jobs — as opposed, presumably, to those who go to school, are between jobs or live off the proceeds of their trust funds — are more than twice as likely to access the Internet from their phone as working Americans who own Research in Motion (RIMM) BlackBerries, Palm (PALM), or Microsoft (MSFT) Windows Mobile devices, according to a report issued Friday by Forrester Research.

????Based on a mail survey of 61,033 Americans fielded in February and March 2008 — back when iPhones started at $499 (not $99) and had only been available for six months — the study found “a quantitative difference in what working iPhone owners do.”

????In particular, the authors found that:

????? Working iPhone owners are more than twice as likely to use the mobile Internet. While only 9% of mobile phone owners and 38% of all working smartphone owners access the Internet from their phone at least weekly, a massive 78% of working iPhone owners do so.

????? Mobile email and texting are much more common among working iPhone owners. Whereas one in two working smartphone owners sends mobile email at least weekly, more than three in four working iPhone owners do so. And 80% of working iPhone owners text weekly in contrast with 60% of working smartphone owners and 36% of working mobile phone owners.

????? Households that own iPhones spend more on mobile bills than the average mobile household. Working iPhone owners as a group spend $87 on their household mobile phone bills monthly, while all working smartphone households spend $76 and working mobile phone households spend $66 per month.

????? Working iPhone owners are twice as likely as all mobile users to go online in public. In addition to home and work, the two most common places to go online, more than a third of working iPhone owners go online outside or in another public place. This is twice as many as all working mobile phone owners (17%) and nine percentage points higher than all working smartphone owners (26%).

????? Fifty percent are more likely to read a blog weekly. Twenty-three percent of working iPhone owners read a blog at least weekly, whereas only 16% of working smartphone owners and 11% of working mobile owner owners do so. This blogging difference extends to maintaining a blog as well, where working iPhone owners are almost twice as likely to do so.

????? A third are more likely to maintain a social networking profile weekly. Twenty-six percent of working iPhone owners maintain profiles on social networks, while only 19% of working smartphone owners and 14% of working mobile phone owners do.

????? Twenty percent are more likely to use instant messaging weekly. Forty-four percent of working iPhone owners uses instant messaging at least weekly versus 37% of working smartphone owners and 24% of all working mobile phone owners.

????? More working iPhone owners telecommute and access the network from home. Twenty-eight percent of working iPhone owners telecommute regularly, and 42% regularly access an employer’s network from a computer while at home. This is a greater percentage than is found among working smartphone owners, where only 20% telecommute regularly and 34% access an employer’s network regularly from home.

????? Although more connected to work, fewer iPhone owners bring laptops home. Despite this greater tendency to telecommute and access an employer’s network from home, working iPhone owners are less likely to bring a work laptop home (36%) compared with all working smartphone owners (42%).

????The full report is available here as a downloadable PDF for $749 — with a three-week money-back guarantee.

????Below the fold: A sample graphic showing that iPhone owners are younger and richer than the general smartphone population.