Depends on how exactly you want to achieve this.
If you have/want to zip the files from within Informatica, have fun, then I would use either Java Transformation or a shell script / batch file.
If you want to "only" invoke a web service which takes the zipped archive and moves it to the final destination, then you will have some fun implementing that web service but you can invoke it from within the INFA platform or PowerCenter simply by a Web Service Consumer transformation.
If you have to provide a web service in INFA platform / PowerCenter which provides this functionality, then you will need the Web Service Hub license plus Real-Time Option (if memory serves me right). And in addition you will have the same "fun" part of zipping a whole bunch of files in platform / PowerCenter (see my first remark).
Does that help? I know it's very short.
Thanks Nico. Figured out through the web services consumer transformation.