She's Sensor Girl, the former Princess Projectra. The recently deceased husband she refers to is Karate Kid who died in Countdown.
The revelation of her ID makes better sense of her earlier comment about Mon-El not being dead - as a future teammate she obviously knows what will happen to him here.
Sensor Girl, hmmph. Its surprising to here reference to Countdown. It will be very surprising if they reference Jimmy Olsen's role from Countdown
in this title. Was he in this ish of Guardian..err..Superman #692? Wonder if that LSH guy in JSA will be involved with the dead Mon-El plotline going on.