It's been used selectively but regularly recently - Google Earth have effectively released their resource to media companies worldwide WITH a strict proviso that the source is prominently acknowledged.
Most Google Earth images come from
http://www.digitalglobe.com/ and they have the following usage guidelines
Editorial Usage Rules For QuickBird Images
1. Editorial Use Only. DigitalGlobe products made available in the “Images For The Media” or similar area of the DigitalGlobe website may be published for editorial use only, in hardcopy, electronic or in broadcast format, provided that credit is conspicuously provided to “DigitalGlobe” on all such products as set forth below. For purposes of these Usage Rules, “editorial use” is limited to a publication relating to a newsworthy event, or which is otherwise in the public interest.
2. Attribution Rules. All DigitalGlobe products published or otherwise used pursuant to these Usage Rules must be attributed to DigitalGlobe as follows:
For print, presentation and Web materials:
Credit to DigitalGlobe must appear next to or beneath the photo.
For broadcast:
Credit to DigitalGlobe must appear on-screen throughout the entire air-time of the product. Additionally, if the products are referenced verbally during the program, they must be verbally attributed to DigitalGlobe.
3. No Commercial Use. Except for the limited rights set forth in these Usage Rules, DigitalGlobe retains all rights to the DigitalGlobe products, and any commercial, promotional or other use requires the express written consent of DigitalGlobe, Inc.
4. No Alteration. No image published or otherwise used pursuant to these Usage Rules may be modified, altered or supplemented in any way without the express written consent of DigitalGlobe, Inc.
5. Limited Grant of Rights. The rights provided in these Usage Rules by DigitalGlobe may be revoked at any time by written notice of DigitalGlobe.