This is absolutely new to the BlackBerry platform as there is no such tool available by now. Well, it is possible to somehow compress a file to a GZip (.gz) file. However, this application will also be able to compress complete file structures including directories with their subdirectories and files. Of course, extracting will be available as well.
This will be really interesting as it will be possible to compress some files and then send them attached via email to your buddy.