Clark and Lex Reunite for Smallville Finale [Pic]

Here you have it: the first pic of Lex's triumphant (?) return to Smallville for the series finale. So many questions - what convinced Michael Rosenbaum to reprise his role as Lex, after maintaining for some time that he would never return to the show? Why is Clark wearing formal wear? What is the reason for Lex's smug grin (never a good sign)? The answers to these and many more questions will doubtless be answered soon, as the epic Smallville series finale is very nearly upon us. Whatever changed his mind, I'm super-psyched that the excellent Rosenbaum will be back to send the series off in style.