Here is a set of predictions and spoilers that I gathered from the Browse Inside for Fading Echoes and from other sources. Enjoy!
In the prologue, Hawkfrost is sent by Tigerstar to visit a cat in her dreams and to attempt to sway her to join the side of the dark forest. It is said that this cat has 'great power', which may imply that it is Dovepaw. However, the blurb for the next book, Night Whispers, states that there are dark forces 'preying upon one cat's jealousy.' This seems to imply Ivypaw (or Hollyleaf?). This could simply mean that the Dark Forest will try to get both of them, but we can't be sure.
The prologue also reveals that Breezepelt is being trained by Tigerstar, Hawkfrost, Darkstripe, and Brokenstar. Breezepelt says that he hates Crowfeather, calling him a traitor. Tigerstar urges him to get revenge on all of the cats who betrayed him and Breezepelt says that he will get revenge starting with Crowfeather. This may mean that Breezepelt will try to kill Crowfeather sometime in the future.
Leopardstar dies in this book and Mistystar becomes the new leader of RiverClan.
Ivypaw gets a splinter from Jayfeather's stick, and Brambleclaw throws it in the lake to prevent others from being hurt by it. At the same time Jayfeather gets an unexplained pain in his side, as though he was stabbed by a thorn. There is no blood (which seems strange to Jayfeather), but it hurts for a while. Lionblaze later tells Jayfeather about what happened to the stick, and Jayfeather explains to Lionblaze a bit about the stick and the ancient cats.
Jayfeather is getting really good at using his powers. He can now read cat's memories at will, and can read the overall mood of all the cats in camp at a glance. For example, in the book he reads Mothwing's recent memories because he is curious about what she was thinking at Mistystar's leader ceremony, and when he is going out into the forest with Lionblaze he checks the mood of all the cats in camp to see if anyone needs anything before he leaves. Jayfeather also reads Lionblaze's memories when he is explaining to him about the significance of the tunnels, and Lionblaze notices this and tells him to stop. Also, Dovepaw has been practicing using her powers. She can see what is happening in RiverClan camp while she is standing in ThunderClan camp, which demonstrates how good her senses really are.
Both Jayfeather and Lionblaze have grown up quite a bit. You may have already noticed this from 'The Fourth Apprentice', but Lionblaze is not as battle hungry as he was in his youth. He knows that there are usually better solutions than fighting, and he has a bit more sense than Dovepaw in a lot of areas. (See the below paragraph.) Jayfeather has also grown up, and he is now a very wise medicine cat. He demonstrates this when Dovepaw comes to him after having a nightmare about Rippletail's *?* death that occurred on the journey in 'The Fourth Apprentice'. Even though Dovepaw doesn't tell Jayfeather anything, he immediately perceives that she is upset and determines after a moment that Dovepaw still blames herself for Rippletail's death. He comforts her by saying that it wasn't her fault, and that Rippletail knew exactly what she was doing. Jayfeather's wise counsel puts Dovepaw's mind at rest and she leaves feeling much better. Jayfeather has also learned a bit more self-control, and he avoids intruding on the thoughts of his clan mates unless he has a good reason to.
While training, Dovepaw hears Sedgewhisker being attacked by dogs and asks Lionblaze if they can go help. Lionblaze refuses, saying that WindClan can solve their own problems. Dovepaw is not convinced, and sneaks off with Ivypaw later that night to see if Sedgewhisker is okay. While trying to talk to him, they wake the entire WindClan camp and are reprimanded by Sedgewhisker, who says that they can solve their own problems. (Which was almost exactly what Lionblaze said to Dovepaw earlier.) Dovepaw and Ivypaw are escorted back to ThunderClan camp by two WindClan cats. When they arrive they manage to wake the whole of ThunderClan as well, and Firestar takes Dovepaw, Ivypaw, Cinderheart, Lionblaze, Jayfeather, and the two WindClan cats out into the forest to talk. After sharply reprimanding Dovepaw and Ivypaw, Firestar sends Cinderheart, Ivypaw, and the two WindClan cats away, saying that he wants an extra word with Dovepaw. This leaves Firestar alone with Lionblaze, Jayfeather, and Dovepaw. I think you know whatâ€™s coming next.
It looks as though Firestar is about to finally find out about the cats from the prophecy. As I said many times in the past, it seems that he already knew a bit more than he was letting on. The book preview ends right before he finds out about the three, but before it ended he singled out Lionblaze, Dovepaw, and Jayfeather, which may suggest that he already has his suspicions about who the cats from the prophecy are. The browse inside preview ends with Firestar asking Dovepaw how she knew that Sedgewhisker was being attacked by dogs, with only Firestar and the three around to hear her answer. Pretty suspenseful place to end it hu?
On another note, there is still no sign of Hollyleaf. She was mentioned once or twice in the book, but once again they avoid directly saying that she died. Instead they say 'was lost' or 'disappeared'. For more information on this, read my article: 'Why I believe that Hollyleaf is not Dead'.