The Atom summary should be kept in the aggregated feed

[stof]

A good example is the feed of thephp.cc which uses <summary> too provide an extract of the blog post.
In the aggregated feed, the summary is removed, making the item quite useless (we only have the title) and is probably one of the reason why some PHPUnit-related post were missed (having the title alone does not encourage to go read the blog post).

see this discussion for some insight: https://twitter.com/s_bergmann/status/467306873495228417