2x04 - Duet

WEIR: No. Lieutenant Cadman is still in there somewhere. Did you know her well?
BECKETT: No, not really. She was with the new batch that came aboard the Daedalus. She seemed quite lovely, though. She saved my life.
WEIR: Well, you'll be the first person I call when we find her.
BECKETT: Thank you.

BECKETT: Oh. Well, yes, then, she seems like a lovely lady.

2x12 - Epiphany

BECKETT: Aye, and besides that, I have a date planned with Lieutenant Cadman for tomorrow night.

3x10 - The Return

SHEPPARD: You should call her.
McKAY (agreeing with him): Mmm.
BECKETT: Who, Cadman?
WEIR: You guys did make a cute couple.
BECKETT: It didn’t work out. May have something to do with our first kiss being through Rodney!

Gateworld.net Audio Interview With Paul McGillion

GW: Any chance of Beckett continuing his relationship with Cadman this year, or seeing signs of that in the dialogue even if she doesn't show up?
PM: I don't know, as of yet. I don't know. It would be nice, that's for sure.

The Scifi World Interview With Paul McGillion

Gilles Nuytens: It seems that Lt. Laura Cadman, played by Jaime Ray Newman, has some affinity with Dr Beckett, how will this relationship evolve ? Will anything happen this year between them ?
Paul McGillion: [re: season 2] I will say that we do see Cadman in more than one episode this year. My lips are sealed and there can be no pillow talk from me!

Wikipedia

It appears that Dr. Beckett is pursuing the relationship that she struck up with him during the situation in "Duet" [3] There is also evidence of an on going relationship in the episode "Michael"; Carson's calendar is marked with "dinner with Cadman" on it.