"Before I even start with this post I must make a disclaimer: The process I?m about to describe works great for me and I have had no problems as a result of using this process. ?however I do not guarantee anything and you should back up your Aperture data before attempting anything in this blog post. I am not responsible for your data."
Continued at http://www.oreillynet.com/digitalmedia/blog/2006/11/syncing_aperture_libraries_on.html
.