Until now, Google Blog Search has indexed primarily via RSS feeds, which meant that for blogs that published partial feeds, Google Blog Search only indexed that partial portion. Any links or text in the rest of the post weren’t available through Blog Search. (The full posts were indexed in web search, of course.), reports Vanessa Fox.
"We have changed the way we index blog posts to include the full content of the page. We've had occasional complaints about the use of the feed content, particularly the problem with partial feeds. The indexing change has improved the results for a lot of queries, both because we have the full content of the page and because we extract links that are missing from the feeds. The downside of this change is that we see more results that match only the blogroll and other parts of the page that are common to all of a blog's posts," explains Jeremy Hylton.
Source:→ Google System