First of all thanks for attending Google Developer Day yesterday, we hope you found it useful. Unfortunately, we need to let you know about an incident which took place during the conference which you may need to take precautionary action on.
We identified unauthorised activity on the public wired Ethernet network which was provided by the convention centre for conference attendees to access the Internet. This may have affected a limited number of attendees accessing websites and online applications through the wired Ethernet connection. We have no evidence so far to suggest that the wireless network also provided at the event, and which was used by most attendees, was affected.
Due to the unauthorised activity, there is a chance that if you used the wired network, any user name and password entered to access a website may have been put at risk. When trying to access a secure website (a website using https), you may have received an alert indicating that the page had an invalid security certificate. In any case, we advise users as a precaution to change the passwords for any websites or services they accessed through the wired connection during the conference.
We're really sorry that this has happened but we believe that the vast majority of attendees won't have been affected by this incident. In the meantime, we look forward to seeing you at future events very soon.
The Google Developer Day Team