Lucian Plesea, the brains behind the OnEarth server, has told us that it will be a few days until the server is completely online. As I stated above, some services are available (beta version can get Landsat tiles, for example). But the elevation dataset will not be available for a few days.
The server is actually up, but DNS records and firewalls take some time to get cleared on the JPL (Nasa) side.
We'll keep checking and post here when things are back online.
Thanks.