Microsoft says that sites which use Internet Explorer 9′s new ‘pinning’ feature have seen a huge increase in traffic.

‘Pinning’ is a new feature in Internet Explorer 9 for Windows 7 that allows web developers to create additional features straight into the Windows 7 superbar. Windows 7 users can pin sites to the superbar and easily access their favorite sites. Web developers can also include notification features and contextual menus.

Microsoft says that site owners who have implemented the new feature have seen an increase in site visits, anywhere from 15% to 50%. “It shouldn’t surprise that much,” Brian Hall, general manager of Windows Live business group, told CNET in an interview last week. “If you think about it there’s a reason people have competed aggressively for default home paging for years and years and years. That default home page was the thing that you saw every time you started your browser,” Hall said.

Microsoft says that so far more than 900 sites have taken advantage of the new feature. “I think what you’ll find is, the more sites that do pinning, the more people want to pin. You might see more people going into double height, but that’s a problem we look forward to having,” Hall said.

Microsoft launched its final development milestone version of Internet Explorer 9 on February 10. Microsoft’s main change in Internet Explorer 9 RC is the addition of Tracking Protection. The new privacy feature allows consumers to address their concerns about being tracked on the web. Internet Explorer 9  RC offers users a new opt-in mechanism to identify and block many forms of undesired tracking such as cookies, web beacons, advertisements and trackers. Tracking protection involves lists that can be published online.

Tracking protection works by allowing users to create lists of sites that are protected from being tracked by other sites via cookies and other means. Microsoft expects technical users to create lists initially followed by consumers once Internet Explorer 9 is generally available later this year. Microsoft originally promised not to include a default list but it appears some Google Analytics blocks are part of a dummy list supplied with Internet Explorer 9 RC, although are not enabled by default.

Microsoft’s second security enhancement is the ability to block ActiveX controls. Internet Explorer 9 RC includes an “ActiveX filter” option. The filter allows users to switch off ActiveX elements within their session, furthering Microsoft’s commitment to security within its browser. The filter is basic and doesn’t appear to allow for a per-site setting, just on or off.

Microsoft announced earlier this month that the beta version of Internet Explorer 9 has surpassed 20 million downloads, making it the most downloaded beta release of Internet Explorer ever. The download rate of Internet Explorer 9 beta has grown by 5 million each month since its release on September 15, 2010. Microsoft is expected to reveal the final version of Internet Explorer 9 at MIX 11 in April.