It can, as far as I know, actually be done, but only for Stones, Terrains, and Symetrical Lattices. All you do is select the Stone/Terrain/Lattice, click the little 'E' then press CTRL-D. You should then get the option to export it to .X, amongst other things. Unfortunately, anything else cannot be exported.
Here's a little link to the DAZ forum about this very topic:
http://forum.daz3d.com/viewtopic.php...8345d6f00e24c9
And according to one of the Forum Team: "Since Bryce primitives/booleans are calculated at render time, they're not "true meshes". Any export capability would have to figure out how to convert them to something that is useable in another program. That's not an easy task."