First this morning came the update to post-Katrina imagery for New Orleans in Google Maps and Earth’s base layer, and now an explanatory blog post by Google Earth general manager John Hanke. In it he confirms:

• The post-Katrina imagery was removed from the base layer way back in September 2006, and nobody noticed until now.
• The post-Katrina imagery has remained available since then via several network links downloadable from this site, for example this network link.
• The new updated imagery of New Orleans is from 2006 and its publication was expedited after the outcry over the past few days.

The new imagery comes with no credit/sourcing, so it’s not clear whose it is.