Using cleartool I am able to find all the files associated with a label using something like:
ct find -avobs -version "lbtype (Build-Label)" -print
How do I find all objects changed (including adds and deletes) between two labels?
Answer
In ClearCase (under Administration in my install) there is Report Builder. Under Elements/Labels you can select either "Elements Changed Between Two Labels" or "Versions Changed Between Two Labels" depending on which you need. You can then select the path to analyze and select the two labels to compare.
After the process runs you have the option to save the results as HTML, XML, or CSV.