Batman on Film are also reporting it:
I've no idea if this is true. I hope it is and if its a Justice League film, bring back Ryan Reynolds as Green Lantern. If they adapt (albeit loosely) the plot of the first New 52 Justice League story I can totally see the scene between Batman and Green Lantern being played by Bale and Reynolds:
"Don't tell me you're just a normal guy in a bat cape!"
If its just World's Finest, how about Public Enemies?