Currently, the subversion plugin allows downloading multiple modules, and the URL of the module takes care of whether you are getting files from trunk, or a tag or branch.
For CVS, you can specify multiple modules for download, but only a single tag/branch for all of them. Would it be possible to allow downloads from multiple branches/tags for CVS modules, just like it is in subversion? We have projects that depend on modules from different branches, and this hampers our use of hudson in this case, unless we manually add the cvs command using the "Execute Shell" option.