Sort of, except that the two forces are not exactly opposed to each other so much as operating in different fashion. Close in, such as on the scale of planets, moons, stars, and galaxies, gravity keeps things in certain alignment. Gravity is the dominant force.
However, on extremely large scales such as that between galaxies, galactic clusters, and supergalaxies, gravity is essentially too weak to affect anything and things are zooming away from each other at faster and faster speeds. It is thought that dark energy is what's driving this pushing effect.
Don't take my answer as fact becasue I am far from the smartest person on this board.
As I understand it, gravity is not a force that "pulls" you in. It's a hill you slide down.
The earth is causing the spacetime around it to curve towards the earth. The curve in spacetime is a kind of slope. The slope is gravity. This a pretty non-scientific explanation. No matter how I hear it explained it only makes me want to understand what the heck spacetime is, how it can curve, and why we slide down it's slopes.
Curving spacetime in the opposite direction would not produce Anti Gravity, because you'd still slide down the hill, just in the opposite direction. So it would still be gravity, I think.
The only opposite I can imagine is flat spacetime. And from what I have posted and read on these forums, it's impossible to get spacetime to flatten out.