Quote - Tearible cloth is seen running, presumably in realtime, in the video linked to above.  I'm guessing each vertex has a stress coefficient, and the polygons seperate when the vertex reaches it.  I don't know why it couldn't be made to do it along a designated seam, don't know much about it beyond what is shown.

I think the best estimate of reasonably viewable results could be gleaned from what the games are doing now.  Bullet is blender's physics engine and runs in real time there, so I have to guess the cloth is also designed to run in real time.  It may run quicker with less polygons than we are now used to modeling.  Maybe it would oly be useful for things like scarves, flags, or maybe it could be grafted to a non cloth-sim to make coattails or sleeves.  I guess it depends on how it works best.  It may handle a lot of low poly cloth sims better than one high poly one or vice versa.

I expect to find out what it can do when/if it becomes part of blender.

Well I think it's safe to say at least some of bullet will get incorporated into FAST, just from the reading I've done thus far it does seem to offer some pretty interesting capabilities.  The tearable cloth looks very interesting, something I'd definately like to persue, but it's going to require some thought on the implementation side.

I'm not certain I want to, as the documentation suggests, base the tearing applicaiton of the physics engine solely on the stress factor placed on the cloth by various unseen forces in the scene.  While that is certainly a good thing for a gaming engine, for the kind of still/animation production I'm considering I think it would be better to allow the user to decide if a section of cloth should be considered "tearable" or not, thus you could have a lot of various components in a scene (like gravity, forward motion, etc) that might in "real life" cause something to rip but you might not necessarily want it to tear in your animation or still.  Think of Indiana Jones, for example, that hat always seems to stay on no matter what sort of forces are applied to it from velocity, wind, gravity, etc - such are desirable characteristics in some production animation or still work.

But giving the user the ability to specify that certain areas of the cloth could be "torn" would be a great ability, so that they could, for example, specify that yes, this shoulder strap should be "tearable" but the other should not, etc - and have the engine consider that in it's calculations.  That way your not stuck trying to figure out exactly how much force to apply in which direction to get the cloth to "rip" just the way you want it.

-Never fear, RenderDog is near!  Oh wait, is that a chew toy?  Yup. ok, nevermind.. go back to fearing...