Google's Q&A Database Different From Web Search Database

This morning I posted at SER that Google was displaying results for a particular site in the Q&A section of the Google SERPs but at the same time does not have any pages of that site listed in the Google web search index.

The details of this were posted in comments at Matt Cutts' blog. The site comes up for a search on % of African American in Los Angeles but does not come up for a site command search.

This may prove that Google uses a different index for the Q&A feature and the web search results.