Tableau should come out with a 64-bit Linux server version. It could use Java and be cross platform. Run the server on Linux or Windows Server. Also, the Desktop could be in Java too. Then it would be cross platform on the desktop. Linux, OS X or Windows.
--> Community Manager update [Ciara Brennan]
Tableau Server on Linux released with version 10.5
(Feature 77070) Tableau 10.5 Features | Tableau Software