It must be tested if the following web page resources are in fact using "far future caching" with the appropriate cache busting technique of having the date of modification as part of the file name.
We must confirm that the proper cache headers are on the served files:
http://developer.yahoo.com/blogs/ydn/high-performance-sites-rule-3-add-expires-header-7181.html

It should be tested on:
1. In the assets app in the thumbnails view.
2. In the page editor & page preview that the renditions of images behave this way.

This is critical for page performance and is also evaluated by seo page ranking robots.