Breaking news is often fluid, but journalists had time to plan Wednesday for news that George Zimmerman would likely face charges in the February shooting death of Trayvon Martin. Florida State Attorney Angela Corey scheduled a 6 p.m. press conference to announce her decision, during which the Top 10 news sites generally updated their homepage once or twice with either a new headline or new photo or both. Based on checks I did every 15 minutes or so, and screenshots I grabbed between 5:50 and 6:55, CNN was the only one of those sites to update the story headline and/or photo more than twice in that hour. Here's how its coverage progressed.

CNN's initial homepage story at 5:57 p.m. -- just before the news conference began -- relied on anonymous sources and photos of Zimmerman and Martin.

By 6:09 p.m., CNN updated its homepage to show that Zimmerman had turned himself in to authorities. The site also used a yellow-and-black "breaking news" banner to signal readers that the story was unfolding.
At 6:21 p.m., there was a photo of special prosecutor Angela Corey, along with a reminder that CNN was streaming her news conference. The "breaking news" banner remains.
By 6:38 p.m., CNN's live streamed coverage had switched to the news conference with Al Sharpton and Trayvon Martin's parents, who were shown on the homepage. Note that the "breaking news" banner is gone, though the yellow "breaking news" label is still on the story and there's now a tweet conveying the information that was in the banner.
At 6:54 p.m., the homepage photo included Sharpton, along with a reminder at the bottom of the photo to "watch live," which had been updated since 6:38 p.m. to say "Martin family, lawyers speak" rather than "Sharpton, Martin family speak."

All these changes -- the headline, the photos, the subheads and streaming tease -- convey to readers that a story is being updated to reflect the most current information.