Jeffrey Friedl has released a set of Lightroom 2 export plug-ins including one feature which really caught my eye - his “Metadata Wrangler” which:

allows you to strip selected metadata components from images as they are exported. You can use it, for example, to remove the embedded thumbnail and any Lightroom “develop” metadata, while retaining other metadata, such as the exposure settings, lens information, copyright, etc.

While this filter can be used with Jeffrey's plug-ins, you can download and install it on its own and use it as part of Lightroom's standard export dialog. And apart from what it does, it's also interesting for how it does it - using the Exiftool tool to post process the exports. Nice work.