I do not think that we will see a Linux version of Terragen .
Jo makes the Mac version. They have to hire another programmer or Jo or Matt had to make the Linux version themselves.
With the progression speed we see now i think waiting for the Linux version would be overly (much overly) optimistic.
They may want it! But making it is another thing.
In fact i wouldn't make a Linux version other then a passion for Linux itself maybe too if i had the call in these circumstances .
I have nothing against Linux or Planetside (i would love to see TG 2 everywhere obviously) just my thoughts about this