Hitwise is reporting that MySpace was the website most visited by US internet users last week. This is the first time that’s happened, the company reports. Yahoo and Google traditionally lead the pack, but Hitwise’s Bill Tancer points out today that MySpace attained a market share figure of 4.5% of all the US Internet visits for the week ending July 8, 2006. Though traffic stats are always hard to determine, Hitwise is establishing itself as one of the most authoritative voices on the subject.

Recent numbers for MySpace put the service at 75 million plus users, 15 million daily unique logins, 240,000 new users per day, and nearly 30 billion monthly page views – that’s 10,593 page views per second.

Perhaps what this means is that for many young people, the social web isn’t a seperate place it’s the web. Once MySpace teams with a powerful search engine, goes multilingual (if that works) and continues expanding into new verticals like the new Books section – then we’ll see if building on the basic social functions the site is famous for will make it stronger. Child safety issues, malware – so much remains to be seen.

Update: Yahoo! has issued a statement in response to the Hitwise data emphasizing that only Yahoo! Mail is included in these numbers. If all of the Yahoo! domains are included then the company remains in the lead. I can’t help but wonder whether the picture would change again if all the News Corporation domains beyond MySpace were included!