This week, a group of hackers released a list of about 5 million Gmail addresses and passwords. This list was not generated as a result of an exploit of WordPress.com, but since a number of emails on the list matched email addresses associated with WordPress.com accounts, we took steps to protect our users.
We downloaded the list, compared it to our user database, and proactively reset over 100,000 accounts for which the password given in the list matched the WordPress.com password. We also sent email notification of the password reset containing instructions for regaining access to the account.
Read the full article @ blog.wordpress.com