For all users who have logged in since the 3.0 upgrade a while back, passwords are salted and hashed with a decent algorithm, and users prior to this point have hashed passwords. (This means if you've logged in any time recently, your password is hard to crack, but not impossible through brute force.)
1.
2. If you are using the same password on this site on other websites, you should change those too, especially if you share a username or email address on those websites.
3. Notify us if you encounter any unusual access to your account.
As we learn more pertinent details, we'll let you know. We value your privacy, which is why we are releasing these details as a precautionary measure. If you have any information regarding this breach, please contact me by email.
We hope nothing worse comes from this, but we want you to be aware and able to prepare for every possibility and for you to be able to secure your data appropriately. We're implementing additional security measures to prevent recurrence of such a breach, so as to better protect you and the site. Thank you.
-mith