Saving the image that somearticle include would be nice. That way you can view article summaries along with their pictures while offline.

Perhaps making this an option having an image cache expiration date would be best.

A more intriguing possibility would be the addition of functionality similar to the Scrapbook extension for Firefox. Vienna could save web pages for all marked articles, then let you flip through them selecting the portion of the page to archive with the mouse cursor (and also adding notes) before saving it.