The licence for Lightroom allows one to run it on their primary PC and laptop as long as both are not running at the same time. Has anyone tried running it on a shared set of images (e.g., on a NAS) between a Windows PC and a Mac? 

Does Lightroom create a local database/change-file or something that would prohibit this? Will I see changes made by each system and not step all over myself doing it?

**EDIT**: Lightroom does keep changes in a local database. However, there is an option for saving changes to XMP files (LR-defined XML files) that are kept with the images. Anyone use this [method](http://blogs.oreilly.com/lightroom/2008/04/have-xmp-will-travel.html) to share images and changes between two computers? 

**EDIT**: This question was originally asked with respect to Lightroom 2.0.