Google announced a feature that lets you download your Google Wave content as a Zip file. Within any wave, you can now select "Export" which will let you save your current view of the wave, plus any attachments that have been added along the way. We hope this feature proves a useful way of sharing the information that you have in waves.
This feature is useful if you have a few waves that you want to export. We are aiming to have a export method for those that have a lot of waves, and will let you know when that's available.
For more information on it, visit this help center article.