From the Illumos announcement page:
Illumos will be announced publicly at a conference call on Aug 3, 1PM, EDT.

To join this call, head over to the below link, and register your mail ID for the call information.

You can join in two ways:
Call in via phone
Call via Voip (mic/speakers)
The access details will be sent in an email once you register.
Aug3, 1pm EDT is 19:00 in Berlin (CEST), 18:00 in London(BST) and August 4th, 1:00 in Singapore.

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