TensorFlow SIGs and other groups hold regular meetings via videoconference. Usually you will find these added to your calendar after you join the Google Group relevant to the SIG or community group.
There is also a master calendar listing all community meetings: TensorFlow Community Calendar.
Google Calendar users can add the calendar to theirs using the button on the bottom of the master calendar page. If you want to add the Community Calendar to your own calendar application, use this iCal link.