Atfer a long weekend the challenge was met!
The fully aggregated feed for all the 400 blogs LISZEN searches and I could find a rss feed for (with a valid and inteligible datestamp) is from now on (and forever) available at http://last25.janjos.com/ with a complimentary rss feed at http://last25.janjos.com/rss.php (I think that due to a glitch in my php.ini it now searches only the last 24 hours)
Update time is at each 15 minutes (00, 15, 30 and 45) of every hour!
Share and Enjoy!!!