From the Google Blog
“Today we’re launching the Google Blog Search Pinging Service, which is a way for individual bloggers and blog platform providers to inform us of content changes. Blogging providers who syndicate RSS/Atom/XML and want to be included in our Blog Search index can now ping us directly. We’ll continue to monitor other pinging services and will contribute change notifications to the community. Read more at our FAQ”
This makes so much sense I am surprised they did not have this from the start but glad to know they are doing more to bring in fresh content.