Valve Pulls Its Unreleased Linux Client From Server
We even ended up finding the unreleased Linux files on the Valve servers.
These files included the Steam Linux client binary and all of the other Linux libraries that are needed for the client. These files haven't just been sitting around, but Valve has actively been updating.
Unfortunately, as of today, Valve has pulled the index file from their server and the related bins_linux.zip and steam_linux.zip (or they have just been updated and due to the lack of the index file we don't know the new checksums).