Can somebody tell me if there is a driver available to use the FXT009 on a mac-mini OSX Lion?
What kind of “driver”, exactly, are you looking for?
What is your Use Case 
I want to receive SMS messages on a mac-mini server. Can I just plug and play the modem?
Just use AT Commands on a serial port. Commercial & Open-Source solutions exist.
If you need the USB drivers, contact your Distributor.
For a Server, it might be better to use an SMS gateway
We are setting up a message wall software for the event industry. We only want to collect the sms and push them to another DB and the FXT009 solutions works fine for that in a Windows environment. I prefer to use mac server though.
Problem is that my distributor can not provide me with the necessary USB driver.
Thanks for the tips.