We ran into this today as well - it looks like the most recent Chrome update will not allow you to display embedded/iframe content in a a page that differs from the default transport protocol, which has been mucking up our Sites. That is, since Sites pages are served via HTTPS, content in an iframe that is served via HTTP.
There may be a Chrome setting that can be changed (there may be some security risk to setting the flag to allow insecure content) via the command line upon launch:
But I'd encourage everyone to report this as a bug, since Chrome's newest update BREAKS GOOGLE SITES, which seems like something they'd rather not do :)
-JP