This morning, the Steam forums went down for “maintenance”. However, it was later revealed that this maintenance downtime was caused by a breach of security in the Steam forums. Later, it was found that the security breach went past the forums, and could potentially include identifying information about users.
Right now, the investigation into the hack is still in its early stages. However, to Valve’s credit, they immediately advised that all users change their passwords — a mandatory password change will be implemented once the forums are back online. Though Steam accounts and forum accounts are separate, it’s probably a good idea to change your password on both of these accounts.
The information that was compromised could include mailing addresses, passwords, email addresses, encrypted credit card numbers and game purchase history, though nothing has been confirmed yet.