From Ask Ausiello: (via TWoP)
Question: Happy holiday hangover! Care to start off my new year with some new spoilers from Smallville?- Frances
Ausiello: Forget "Justice League." Heck, forget "Crimson." The Smallville episode everyone will be talking about is "Labyrinth" (aka Season 6, Episode 12). Sandwiched between "J.L." and "Crimson," the hourlong twistapalooza will answer the question, "What if Clark's super-abilities were nothing more than a figment of his imagination?" The mind-bending episode will also feature the death of a Smallville heroine (hint: I get more questions about this individual than anyone else on the show), and the long-awaited arrival/return of a DC Comics icon. Hey, you know what I've got a hankering for? An Oreo cookie!
Question: Do you have any info on the status of Lex and Lana's relationship? Are they gonna get married or not?- Gillian
Ausiello: There will be a wedding ceremony later this season, but that doesn't necessarily mean anyone's getting married.
All I can say is..."Labyrinth" better live up to the hype. And I love the "figment of imagination" idea of the episode.