Have you noticed the organic results from Google recently?
Try searching for [add url] or [submit a site] in Google. After the top 5 organic search results, you’ll see inserted results for [add url to google] or [submit a site to google]! The image below is a screenshot of the the organic search results from Google for [add url].
It seems that the searches are being refined to include search terms that could be more relevant.
Now try searching for [add your url], [submitting a site] or [adding url]. No additional resuts are being inserted.
For those interested, see more examples and discussion threads at different forums like WebmasterWorld.