Episode 1.12 will be called “Omega” and will air on the 8th May 2009 [SpoilerTV].

I've heard some people say that the episode will be about a new active but I should remind you that all actives are names taken from the phonetic alphabet and "Omega" is from the Greek alphabet. It's more likely that this is about Alpha, possibly derived from the quote:

"And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely."