Hi Tony,
I think that the best answer for this question is “not quite yet”.
The Server Extension uses triggers, a feature that has only been available since Tamino 4.1 - which is only in public release for Windows platforms at the moment.
Once the Unix versions of Tamino 4.1 (and higher) become available, we will also support the Server Extension on those platforms.
As you mentioned, the Server Extension is implemented in Java, so I do not expect there to be big problems with using the same binaries on different platforms.
We will run the test suite on the different platforms though, just in case… 
If you let me know which specific Unix versions your customers are interested in, I will put those on the top of the testing list.
Greetings,
Trevor.
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