The long-and-short of the situation is this: if you downloaded and installed the most recent version of WordPress from wordpress.org in the last few days, you weren't downloading the official release– you were downloading a modified version that likely includes some sort of back-door.
Although only a subset of in-the-wild copies of 2.1.1 contain the vulnerability, the development team has declared the entire release "dangerous," and highly suggest all users upgrade to 2.1.2.
