Lenny: Hi! I don't know about Bryce that much - though you can create mountain ranges.
Adding natural objects to a Bryce Scene
I use max/Maya and yes you can used any image in photoshop as a texture map and bung it on a sphere to make a planet. I've got an WIP for my own planet and following this tutorial...
[tutorial.stavit.cz] - tutorials, instructions, manuals, techniques for 3D studio MAX/VIZ - modeling, texturing, animating, ...
...but it doesnt have to be that complex if you want to do something for your reference. 3D programs have various types of mapping which are based on primative objects like a cube,cylider, cone and a sphere, spherical mapping would be what you're after.
You'll need to pay attention to your poles if you want them to look good too, because a 3d program is likely to 'pinch' and distort your texture there. Your texture will need to be a rectangle and tile on the L & R edges (PS has a filter that will help you do this 'Offset' found in filter>other>offset )
Here's a site that will show you what your map should conform to:
Planet Texture Map Collection they have pretty good planets of our solar system.
If all you want is to map your , err...map on a sphere it would take you seconds to do once you've got your texture set up.
There is also a plugin for PS that you can create cool planets in an instant. you can play with various weathers, sealevels atmospheres and this plugin has a free trial period.
Flaming Pearroducts:LunarCell
There's also Mojo world creator which is based on fractal generation. This has some really great stuff going on. Something else I wanna get around to doing - perhaps when I get to illustrate my SF novels one day!
Pandromeda : Gallery : Stills
Jez