Visitors to the Web site were infected with an exploit code tailored to their browser. Assuming that the visitors were vulnerable, password stealing code was installed and executed on their desktops, without requiring any user intervention...
This is a Microsoft site, hosted by a partner. We are actively working with Microsoft's security personnel to fix the issue.
The SANS Internet Storm Center is reporting that the infection occurred via SQL injection.
From my checks, it appears that the MSNBC Turkish site is now clean and the Chinese exploit server is down.