We've found the problem that prevented my Flex Data Services demos from working last night in London. And in case anyone else runs into this one, here's the scoop.
The FDS installation contains a file named flex-enterprise-services.xml which (among other things) defines the channels used for player to FDS communication. The default RTMP channel has a URI defined as rtmp://{server.name}:2038/{context.root}/rtmp, and context.root could not be resolved. Removing {context.root}/ fixed the problem.
Thanks to Pete Farland for figuring this one out for me (long distance via a Breeze shared desktop).
--- Ben
If your samples were working with this uri (rtmp://{server.name}:2038/rtmp ) it seems that's the gotcha. Maybe the player was trying to connect to rtmp://{server.name}:2038/flex/rtmp.