Rapid adoption of the iPhone 3G has led iPhone Safari’s browser usage share to jump 58% in one month, going from .19% in July to .30% in August. If the trend continues, iPhone Safari’s browser share is on target to see at least 500% annual growth.

To put the current numbers in perspective, about 1 out of 300 visits to an average site are now coming from iPhones. Tech sites and sites that appeal to Apple owners are likely to get a much higher portion of their traffic from iPhones.

Last year, we predicted that, if Apple met its sales goals for the iPhone, the iPhone’s browser share will hit 1% by the end of 2008. That prediction looks a little aggressive, with only 4 months left in the year. Apple’s is likely to sell a large number of iPhones going up the holidays that won’t be activated and being used to surf the Web until a month into next year.

No matter when Apple’s iPhone Safari hits 1% browser share, though, it will be an important milestone for the mobile Web. Mobile Internet use is being propelled forward by the iPhone, and the trend will affect how not just new media and social networking sites are used, but all sites.