I have an idea s to how to do it. But i'm not really sure.

My idea is to have a building and then 
to use Vue to create a version of the building with a piece cut off. 
We can do this using boolean operations. BUILDING minus a terrain or someting that creates a random  surface. I've done it  before so i know it works.

However, when you do boolean, i don't think the boolean shaped object is exported correctly.. So if open in poser, it would n ot look right.

Also, when we do boolean, the original texture map is lost and the object turns grey.

So but anyways,, then what we do is 

1)Open object in poser.. set up your scene. have the original building and the modified one in your scene, but have the modified one totally out of sight. Maybe yTrans -1000 so you sure it won't be seen. Then at the exact time when the building hits the ground, 
use a constant keyframe on both the modified and the original and swap them. The original will be at yTrans -1000, and the modified we will put where the original was landing. 

At the exact time..Start an animation using a group or rocks spreading out in all directions. this will be the debri.  For this we can do it in layers that we can put together in Finalcut( i have it). 
Layer 1 will be poser video of building hitting ground Layer 2 will be an animated smoke video layer. And Layer 3 will be the fast poser animation of debree spreading out in all directions. 

Although i talked here about animating a building hitting the ground. we can eevn do this same kind of swap for say a Tank shooting  a building and creating damage. 

Attached Link: Poser Physics

Actually, there *is* a sort of "Load, tweak, and go" way of doing this, with Poser Physics.  I haven't used it since it was in beta, but, for what it is, it's actually a pretty decent looking program for Poser.

Booleans tend to produce lots of long, thin facets which Poser won't render nicely - they're best avoided. I'd probably try to do that sort of thing in a modeller that has a knife tool, or something similar - I think most do. Even Anim8or has one. :) However you would then have to fill in the cut edges and UV map them so they would take a texture. It's all a bit time consuming - I know, I've done it myself.

Swapping objects in a scene can be done by rapidly translating them into / out of sight - but why not just split your animation at this point, and splice the two together?

Jen - correct me if I'm wrong, but I didn't think Poser Physics could actually break something. It can determine the interactions and paths of the broken bits, but actually shattering something procedurally is difficult even for the top dogs of CGI - although I understand they're working on it.

Powerage has some good breakable buildings in their store here.

It can't actually "break" something, but, if the pieces you set up are individual pieces and not solid, when something knocks into it, you can set them to "fall", or faking a break.

Attached Link: http://www.renderosity.com/mod/bcs/index.php?keyword=breaking

PowerAge has a number of breakaway products.

 Great tips everybody.

 Hey guys. I Decided that all i will need is the quick swap prop technique. 

For the debree and explosions , i will use Explosion stock videos that i found in the web. they're awesome. I'll layer them in Finalcut.

 Oh and guys!!!

The technique  Using BOoleans in Vue to break a part of an object WORKS.. and you can still keep the texure. You just export the boolean and select Generate COlor map.
Then in poser you go to Mterials and select the image map

I have been using Effects Lab Pro and after a lot of practice I have been able to make about anything look as if it's falling apart or exploding with only moderate changes in Poser scene dynamics. As long as the Poser scene is set up to animate everything with consideration to the effect that will be added later in Effects lab Pro, you can do about anything it seems. You might have to create custom effects, though.

I know it seems like a cheap way to do it but with the necessary patience this program is a nice postwork tool.

 I dont have Effects Lab Pro. it sounds nice though.

I'm just going to do my stuff using the Swapping object Poser technique AND use explosions and fire, etc in Final cut. . I do wish though, that POser had a way to break objects so they can form cracks etc

Absolutely, that would be rather nice

 By the way, just a tip for anyone that doesn't know: You can create earthquake motion by animating the camera with random motion.

You can use Periodic Motion python ( available somewhere around Renderosity)script for this. 

I just thought about this, it's a nice effect!!!