Christopher-
I believe you can achieve your stated goal without need for any changes. When a blog editor is prepared to mark an entry as "Published" (from the entry's EDIT screen), simply change the date to the current date. This will insure your blog entries are sorted in the order you wish. I've done this very thing myself when publishing entries I'd begun many months earlier but wanted to publish with the "published" date rather than the "entry created" date.
Dario-
I agree with Christopher that a sorting option would be a nice enhancement. Potential sort variants could include "sort by publish date", "sort by most-recently-updated date", "sort by most-read blogs", "sort by most-commented blogs", "show all entries grouped by parent blog", etc.
If you wanted to make a sorting option really powerful, expose the blog entries' primary data fields as tokens and provide an option for sorting results of REGEX-based pattern matching. (To be admin-friendly you'd want to include some simple REGEX pattern examples to "sort by publish date", etc.) REGEX matching with tokens would allow for searching/sorting by multiple fields and multiple values. Example: Show all entries by editor "A" and editor "C" in the past 3 months with most recent entries shown first.
QUERYSTRING Option
The "sort-by" module setting could be overridden by a querystring value to allow admins an easy link-based solution for users to pick their preferred sort option. This combined with REGEX matching would open up a lot of opportunity for both sorting and advanced user-specified-criteria searches.
-mamlin