Yes, the Blue Marble is the iPhone's default screen, which have been seen by millions of iPhone owners and by everyone who has read about the iPhone in the last 2007 years.
From: *************** <[email protected]>
Subject: Question on Blue Marble image from NASA
Date: March 2, 2010 8:17:49 PM EST
To: Jesus Diaz
Hello. I am the photo editor for the Public Affairs Office at NASA's Goddard Space Flight centre.
We were happy to see you featured our Blue Marble image on your website last week.
We also featured it on our Flickr page but it has really taken off on the web. We had over 500,000 hits in the last two days alone.
Given that this is an image from 2002 I'm just curious what prompted you to post it on your site? Or did you pick it up from someplace other than our site? I see at the bottom it says "NASA via Twitter"
Really, I'm just curious because it's gotten so much play over that few days.
Thank you for your interest in our work.
The reason? Because it's a beautiful image, that's all. One that makes you marvel at the beauty of our planet, and how tiny and insignificant we are, but also how unique and rare. [Thanks to John Hermann for telling me about the obvious]
Don't forget to check NASA Goddard's Flickr page. They keep posting really cool stuff.