That's usually the way it works with partical effects.  The simulation is calculated at render time.  I read somewhere that particle effects are typically done one of 3 ways.  As textured billboards, as metaballs, or as 3D meshes (lots of render time).  Sounds like metaball particle effects are not 3D meshes then?  Unfortunately, I've never played with Carrara's particle system.  The few times I've used particle effects was with Particle Illusion, which is for post render effects.  Hopefully, someone with first hand knowledge of C5's particle system will wander by and give us the exact skinny on exporting.  But off hand, I'd say you are right in thinking that you can't do it.                   

Irene-