From the Myst Worlds site:
I wish I could have given you notice earlier, but there were some details I had to make certain of first. In other news, I finally finished mailing out all the t-shirts I had requested for certain members. So if you were expecting a shirt and still waiting... do not despair! It's on the way. And now that's done, I'll have leftovers that can be given away at PAX, so I hope some of you will be able to make it or happen to be in the area around 8/26-28 and can stop by.We are delighted to announce that we will be offering a hands-on preview of Myst V: End of Ages at the Penny Arcade Expo (PAX) in Bellevue, Washington. Ryan Warzecha of Cyan Worlds has graciously agreed to give the demo of Myst V for us in the BYOC (Bring Your Own Computer) area. Please check out the PAX website for more details about the exposition event.
EDIT: Instead of the BYOC area, we have now arranged for Myst V to be shown within the official Ubisoft pavillion. I hope this will prove much more convenient for everybody.