Ubisoft has suffered a security breach, and while they say no payment information was accessed, but that users should create new passwords (thanks Mashiki). Here's the mail they are sending about this:

Dear Member,

We recently found that one of our Web sites was exploited to gain unauthorized access to some of our online systems. We instantly took steps to close off this access, investigate the incident and begin restoring the integrity of any compromised systems.

During this process, we learned that data had been illegally accessed from our account database, including user names, email addresses and encrypted passwords. Please note that no personal payment information is stored with Ubisoft, meaning your debit/credit card information was safe from this intrusion.