Thanks for your quick reply!
It's quite possible I just don't understand the best way to configure the setup. However, I don't think your solution will work for me...
Let me elaborate on my configuration: My master is Unix, while my slaves are Mac. I want to run the first and last jobs of a diamond build on the master, one of the middle jobs on a Snow Leopard Mac, and all other jobs on a Lion Mac. I have labels for each of these machines to specify their OS type and version. I set up the parameters for the whole build at the first job, and I pass them all to the downstream jobs (Perhaps I need to exclude the node parameter by passing all other values individually??).
If I do as you suggested above, and give a default label for either "master" or "unix", all of the jobs in the whole build will try to run on the master node or a Unix-labeled machine, respectively...regardless of what I specify in the middle jobs, which I want to run on Macs. Honestly, I'm not sure how your suggestion works any differently than specifying a node.