In my book “No Business Like E-Business“, I write about the Google Supplemental Index (GSI – Ravi’s acronym). Basically, this is like the “alternate” Google database, where sites that are “on the way in” or “on the way out” show up.
If yours is a new site, it may show up in the GSI before it shows up in Google’s main index (google.com). Similarly, if your site has suddenly disappeared from the main index, you may find it here (before it disappears from everywhere on Google – which means your site probably violated their webmaster guidelines, and has gotten banned by the Almight G!).
Here’s more information from Google Webmaster Central about the Supplemental Index.
And don’t forget to subscribe to the feed while you’re there.