I've created a reusable set of build files using the technique I outlined at http://stackoverflow.com/questions/5124726/what-are-some-good-ways-to-distribute-a-common-ant-file-to-be-included-in-builds/5168745#5168745. This technique relies heavily on Ant 1.8 importing files from the classpath rather than from a file.
An issue I've run into, however, is how would my reusable build files (the ones embedded in the jar file) load a properties file or resource from that shared jar file? It doesn't appear that by default either <properties resource=""> or <loadresource> has access to resources that are in the originating jar file. I'd specify the classpath but--what would that be? I've tinkered with writing a script or custom task to help me figure out how to get the classpath (or classloader, for that matter) that corresponds to the source jar file, but without any luck. Thanks, Rich