Well, it is a standalone.
It exports every important format: ter, pgm, tga, r32, raw16 (not yet implemented but will be in final release), obj in combination with a normal map (for low resolution terrains for games, comparable to Zbrush), and bmp.
That mean, Vue, Bryce, PovRay, Carrara, Terragen, Mojoworld, 3DSmax with Dreamscaper Plugin, can use the high resolution terrains (16bit). All others can use the geometry with additional normal map.

At time import of 16bit tiff is not surported. Import is ter, r32, pgm, tga and any images (greyscale or colour, bmp, jpg and png)

Worldmachine is the may be most powerful generator on the market. The approach of GeoControl is totally different. It is much easyer to use, more landscape orientated, for example you do not choose a noise algorithmus but a landshape (moutain, hill ...).
It has 22 different landscape forming filters, which can be combined (max 48 filters for one terrain).
And it has a revolutionary new generation system:
Dynamic Level Generation. This enables the user to have much more control over the generating process and to use the revolutionary brush tool of GeoControl. It is a totally different brush, and so, at first a bit strange. But this brush never destroy the terrain surface, as other brushes, you can change the height so often you want, and the terrain still is a terrain. The brush can also apply different filtersettings to different parts of the terrain.

So it is not equal to other terrain generators. But at last, it produces very high qualtiy terrains with a extrem high amount of details and is easy to use.

To price is not fixed yet, but it will be around 50 at the start time.

Johannes