I was just about to get myself together, and ask the same question. It's completely gone, not even the white box anymore & it's been like that for at least a week. Tried different browsers, as well as computers/connections. I miss it.
The Symi Visitor webcam page has stopped working. The reason is that a server that hosted one of the files used on the page closed down on the 27th of April. I put the file on a different server several weeks ago and informed Mike. It seems he hasn't had yet chance to edit the webcam page to use the new server. I'm sure it will be fixed soon.
Meanwhile, the webcam itself is still working and can be viewed at http://symi.webcam (how about that for an easy to remember address?)