While Marvel had grand plans for its superheroes leading up to The Avengers, after the 2012 superhero mash-up things are little more murky, with talk of giving minor heroes they're own movies, as well as the possibility of separate sequels for the characters in The Avengers. Another possiblility that's been rumoured is giving Black Widow her own spin-off flick.
The character first appeared in Iron Man 2, in the shapely for form of Scarlet Johansson, and she's signed a contract that will see her reprise the role in other movies, including The Avengers. Earlier this year, Marvel head honcho Kevin Fiege confirmed a Black Widow flick was a possibility, but now it appears things have moved forward a bit with Fiege telling Superhero Hype that, "We’ve already started discussions with Scarlett about the idea of a solo movie and have begun putting together concepts, but The Avengers comes first."
It's little surprise they're concentrating on the Avengers before getting to invested in a Black Widow movie, as it's an immensely complex undertaking, and a spin-off will only be worth making if people get invested in the character in The Avengers, where her relationship with Hawkeye (Jeremy Renner) is said to play a central role.