Well, by now all the trailers and screenshots have already told us what happened to Jill after Chris and Sheva ditched her for Wesker. Though she does talk to you briefly after over the comm link, plot device declares she be passed out for Josh Stone to find her.
Stone, being a guy who constantly pulls asses out of the fire, wakes Jill up and drags her off. Such is the premise for the "Desperate Escape" DLC. Jill and Stone come with a variety of new moves, though neither has Chris' monstrous arms.
Speaking of Chris, new costumes have been released for download as well, for Chris and Sheva. Costume Pack 2 contains the "Heavy Metal" outfit for Mr. Redfield and a classy "Business" suit for his lovely partner; Capcom guarantees these will add some "flair" to RE5's cutscenes.
Oh, and even if you're not the type to pay for costumes, Capcom's given some incentive to buy both the new mission and Costume Pack 2. Purchasing both add-ons will unlock all eight remaining Mercenaries Reunion characters: Rebecca Chambers, Josh Stone, and costumed Chris and Sheva.
If you're lookin' to buy, "Desperate Escape" is priced at 400 Microsoft Points ($4.99 PSN), and the Costume Pack at 160 MS Points ($1.99 PSN).