No additional details as of yet but Twitch is sending out emails to users of its service details are as such:
We are writing to let you know that there may have been unauthorized access to some of your Twitch user account information, including possibly your Twitch username and associated email address, your password (which was cryptographically protected), the last IP address you logged in from, and any of the following if you provided it to us: first and last name, phone number, address, and date of birth.
For your protection, we have expired your password and stream keys. In addition, if you had connected your account to Twitter or YouTube, we have terminated this connection.
You will be prompted to create a new password the next time you attempt to log into your Twitch account. If applicable, you will also need to re-connect your account to Twitter and YouTube, and re-authenticate through Facebook, once you change your password. We also recommend that you change your password at any other website where you use the same or a similar password.
We apologize for this inconvenience.
The Twitch Team
They are not including a link so its unlikely to be a scam.
I’m glad I have LastPass since having it is ensuring all my passwords are different. Doesn’t help much with personal information though.