I just finished reading up Flashpoint, the latest SC2 novel by Christie Golden. It bridges the gap between WoL and HotS. As they have already stated that HotS begins some time after the events of WoL we can assume that the events of this book will either only be kept within or else summarised at the start of the new campaign.
Below is a summary of what happens in chronological numbered order:
1) The book begins exactly at the end of WoL. Raynor lowers his smoking revolver and picks up Kerrigan.
2) Dropship evacs them off Char.
3) Mutalisks attack on route to Hyperion. They divert to the Bucephalus: Valerian's battlecruiser.
4) Kerrigan is drifting in and out of consiousness. She appears to have regained her human speech and personality, in addition to all her memories as Queen of Blades.
5) Confrontation in Bucephalus hanger bay. Valerian wants Kerrigan studied. Raynor does not.
6) Mengsk warps into the battle with the remaining half of the Dominion fleet.
7) Mengsk orders his son to kill Kerrigan and Raynor.
8) Valerian refuses. He says he wants to study Kerrigan so that the zerg can be defeated for good.
9) Mengsk wants to kill Kerrigan at all costs. He fires on the Bucephalus, willing to kill his son in the process.
10) Both halves of the Dominion fleet begin destroying each other. Valerians fleet, already crippled, gets torn apart.
11) The Hyperion and Bucephalis warp out to safety. Mengsk chases. Valerian loses the entire fleet of 25 battlecruisers. Only the Hyperion and Bucephalis remain.
12) They warp to Deadmans Port for refuge. Matt calls in a favour with Mira Han, who shelters both battlecruisers while they wait for the arrival of Valerians chief scientist, Dr Narud.
13) Kerrigan is regaining her senses while bed stricken.
14) Dr Narud arrives in Deadmans Port. They survive an assassination attempt orchested by the Hyperion bartender, 'Cooper', who remains undetected.
15) Both battlecruisers are under attack by mercenary wraiths. They warp out to the Kirekegaard asteroid belt. Hiding within is the top secret Mobeius facility, the Space Station Prometheus.
16) Kerrigan and Raynor reconcile. Kerrigan appears to be completely human, her presonality and looks Ghost-era, but her hair is still zerg like.
17) Kerrigan agrees to be studied at the Space Station so that they can remove the last zerg mutagens. She arrives along with Egon Stemann (Raynors Scientist), Valerian and Raynor. At this point of time Valerian has proven himself to be one of the good guys and wants to overthrow his father for the good of humanity (sounds familiar).
18) Kerrigan rests on a bed in a isolated ward. Raynor has a private dinner with Valerian and Narud. Stetmann goes to the labs.
19) Narud betrays everybody. He is working for Mengsk. Stetmann is captured and tied up. Raynor and Valerian are surrounded by marines. Kerrigan senses Raynor in danger and regains her full psionic abilities and begins destroying everything.
20) Valerian and Raynor kill the guards and escape, as does Narud with the Artifact (All-In, WoL). Kerrigan rescues Stetmann, who hides behind her for the rest of the novel.
21) Narud unleashes hybrids on Valerian, Raynor and Kerrigan, who are chasing him.
22) The final confrontation happens at the Space Station hanger port. Narud loads his artifact onto a dropship and escapes. A giant hybrid protects his escape in the hanger deck.
23) Mengsk's fleet warps in and destroys the asteroid belt. Both the Hyperion and Bucaphalus are under attack and playing warp around the battlecruiser to buy time.
24) A modified dropship from the Hyperion lands on the hanger deck. It is outfitted with manual guns, controlled by the Hyperion female engineer Annebelle (she is in the cutscenes of WoL and has a portrait in game?)
25) Kerrigan unleashes psionic nova. She kills the hybrid. She also accidently kills Annabelle.
26) They all hightail it out. The Bucaphalus and Hyperion picks them up and they evade capture by flying into stardust(?). They warp to a secure space station within the Umojan Protectorate.
27) After killing Annabelle, Kerrigan agrees to be extensively studied. She allows herself to be sealed in a semi gravity chamber and isolated (the same as can be seen in the HotS trailer).
28) The novel ends. Main points is Kerrigan and Raynors reconcilation. Valerian as a good guy. Kerrigan fully consious, self aware and human but retaining all* her memories. The only thing on her mind is revenge against Mengsk.
It can be assumed from the trailer that the immediate events following this is the insertion of Nova and her ghosts/spectres to locate Kerrigan. Kerrigan breaks free and decides that her best bet to kill Mengsk is to reunite the Swarm. Cue Heart of the Swarm.
*I should note that Kerrigan does not remember Narud, and that while I believe that Christie Golden alludes that she can remember everything else, this might not be actually true.