I can't find the original message, but someone, I believe Stefan had asked whether we could do some tasks that incorporate GPL or LGPL code in this project, since they could not be done as an official part of the Ant project due to licensing conflicts. 
My (possibly dated) understanding of the SourceForge conditions of service require a project to consistently use one license.  I believe at one time, the license was set at project initiation and that the only way to change the license was to abandon the project and start another.
If we determine that there is a worthwhile task that can't be written as a separate work such that the use of GPL software doesn't not require GPL'ing the work (last three paragraphs of section 2 of the GPL, http://www.gnu.org/licenses/gpl.html), then the cleanest way to host that at SourceForge would be to create a new project.  Though, we could still use all this mailing list and other resources to discuss work on the "other" project.
However, I would think that we could find some way to maintain the separate work categorization.  Either by using reflection to bind with the GPL'd code (therefore no access to the GPL'd code would be required to build the task) or distributing the task as source code.