Apple has released another new iPhone 3GS television advertisement, the third in its new series of ads focusing on individual features of the new phone. The latest, “Skateboard,” highlights the 3GS’ video features by showing a person shooting video of a skateboarder, who then uses the on-board editing features to trim out the skater’s fall, and shares the video via email. As with the other two feature-specific iPhone 3GS advertisements,…