OpenSearch results, returned in a standard format (whether that's RSS, RDF, OAI or whatever), would certainly make things easier and less fragile.
To produce a Flitter page at the moment, search results are collected in a number of ways: an XML-based web service for Amazon; text-based web service for Audioscrobbler; RSS for Flickr, del.icio.us and Blogdigger and screen scraping for Feedster.
It must be difficult to fetch results from all the sources listed on the 'add columns' page of A9, so I can see why they want to standardise things.