-By Mike Shields

Mobile Internet usage is exhibiting healthy growth in 2008, as more Americans adapt Web friendly phones while existing users grow more adventurous-- consuming more Web content overall, particularly content that lies outside carriers’ ‘walled garden' environments.

That’s according to a new report issued by mobile technology vendor Crisp Wireless, which claims that the total number of mobile Web impressions generated by users surged by 29.4 percent in the second quarter of this year versus the previous quarter. That estimate is derived from data compiled by Crisp’s Wireless Publisher Network, which includes partners ranging from NBC to Hearst to Turner which in aggregate reach 17 million mobile users each month.

Of course, mobile Internet is still in it’s infancy—Nielsen estimates that 40 million U.S. users accessed the mobile Web last May, while there are at least 200 million wireless subscribers in the country. But Crisp found that as the existing mobile Web user base grows more experienced, they rely less on individual carrier’s prepackaged Web portals – known as “decks” in mobile circles. Positioning on carriers’ decks is seen as crucial by many publishers for traffic growth  in the medium’s early stages.

However, on-deck traffic is declining steadily, according to Crisp’s research. For sites that maintain both on and off-deck presences, the percentage of traffic derived from on-deck exposure declined from 53.4 percent in first quarter of this year to 45.7 percent in the second quarter, said the report.