The creative forces behind Smallville have been hard at work, or have at least pulled out some stops for this episode in their ongoing reinterpretation of the Superman mythology.
OK, I've teased long enough here. If you haven't seen the episode yet, I'm putting out some episode spoilers after the break.
The last wraith from the phantom zone (Bizarro) takes Clark's place (Tom Welling) thinking he's gone and he even fools Lana, (Kristin Kreuk) to the point of us seeing Clark and Lana having a healthy, open relationship that makes Lana happy (and us a brief reprieve from the usual tense subterfuge that goes on between them). However it's taken to the point of them sleeping together and I thought that crossed a line. That made the whole thing much more disturbing than the usual case of mistaken identity.
Meanwhile, Brainiac (James Marsters) played both Clarks against each other to locate the Kryptonian who built him to help repair himself... yes, there is yet another Kryptonian on Earth. Considering the manner in which Brainiac extracts the info he needed, however - I don't think we'll be seeing him again.
Grant (Michael Cassidy) tells Lionel (John Glover) he's a clone of his dead son, Julian. This drives a visible wedge between Lionel and Lex (Michael Rosenbaum) and Lionel is disgusted by this new deed by Lex. With Grant going against Lex's wishes to not tell anyone, Lex has his own cloned brother killed and though Lex is driven to make his point with this deed, it obviously hits home hard as we see the anguish that may finally push Lex over the edge we've all been expecting for seven seasons.
With Lex at a new low, and this Lana / Bizarro thing looking like it's taking it's emotional toll on Clark and Lana (mot to mention, me) I think we're going to see some new, deeper character developments that they are all going to have to confront.