iWork files created from Pages, Numbers and Keynote are all really .zip files containing XML and plist files that describe the formatting. But more importantly, the files also include a PDF representation of the file. So, if someone sends a Pages file to a coworker that lacks the software (even a PC user), all one has to do is unzip the file to get a readable PDF.
In the category of things-I-wish-I-had-known-before-just-now.
