People suspect it will be a place for developers to compete with new technologies, such as HTML5. I guess we will see. Here is a video of the Flash file there now:
In any event, we should find out what the big surprise is some time on Wednesday.
Those in the forum take note that the site is not on a typical Google server. It is running Microsoft IIS and Citrix Netscaler. It is also registered on GoDaddy by a non Google whois record.
Forum discussion at Google Blogoscoped Forums.