>> (Half kidding. It would be great if all who work on aggregator stuff
>> unify their efforts on such an API).
Already there. See http://groups.drupal.org/node/3528
(or the original post at http://drupal.org/node/130942).
Aron Novak's SoC project also addresses this, turning Aggregator module into an API with standard library for parsing, but opening up a pluggable architecture for other modules to replace/extend.
I believe that all the aggregator-type module authors are on board with the new API concept.
If you haven't read the proposed API, now is a good time...
- Ken Rickard
agentrickard