Maybe you are as interested in RSS news feeds as me and are doing a lot of research on them at the moment. Be careful when you come across the term "trusted XML feed"/ "XML trusted feed". You might expect info about RSS feeds, since RSS feeds are a type of XML document and an XML logo is displayed on Web sites that offer news feeds (like this site - learn how to use Robin Good's news feeds). However, apart from being both XML documents, RSS feeds and XML trusted feeds do not have much in common.

XML trusted feeds are XML feeds that have been fed into search-engines by acknowledged, credible business partners in order to guarantee search engine positioning.

Trusted XML feeds are a paid service ("pay-per-click"). This service is relevant for Enterprise-level sites with pages that are difficult to index by crawlers, e.g. because of dynamic content or frames.

Trusted Feed gets around these problems by allowing site owners to have keyword optimised information on each of their web pages input directly into the search engines database via a ‘trusted’ direct data feed, and their listings appear in as little as 48 hours, across some of the worlds largest search engines and portals.
(Excerpt from Greenlight Trusted Feeds Info & FAQ)