[Pacemaker] Run only one resource per node?

[lists at unimitated.com]

Hello all, I've been trying to set my cluster up so that no two  
resources run on the same node together (i.e. each node in the cluster  
runs one and only one resource and if there are not enough nodes  
something does not run).  Is it possible to easily do this with  
colocation constraints or some other way?  I see how to tell pacemaker  
that two resources should not run together but I am not sure how to  
expand that to many resources without having to specify a constraint  
for each resource against every other resource.  Thanks for any help  
getting this going.