Offers E!, "Can't spill anything about the coupling (sorry) but I can tell you what Chloe (Allison Mack) will be up to when she returns to Smallville: She'll be helping to rescue the heroes after what happened in the most recent episode. Prepare for awesomeness!"
"What happened," for those who missed it (SPOILER ALERT!), is that the heroes had gathered in memorium for the fallen Hawkman, when something erupted, rendering all of them unconscious. Apparently Chloe, who the show has hinted has been out there in the world somewhere, reeturns just in the nick of time.