Does the little guy look wild? How big is he?
Wild rabbits, when they are about the size of a tennis ball, go througha phase where they have no fear of humans. They will walk up to you,eat things, and generally act tame. Within four days, they will changecompletely. If the little guy is wild, and you confine him, a few daysfrom now he will be literally bashing his head against the wallsof the cage, and will want nothing to do with you. Caging him couldkill him.
If he's not wild, keeping him in a cage (or thehouse!)is the best thing you could do for him. He wouldn't dowell in the wild, but will have a comfortable and safe life with you.He might take time to adjust but will be fine. Purina pellets, withtimothy hay and small amount of (safe!!!) greens are what he should beeating. Oats are great too.
So if he's tame and larger than what I described, he's probablysomeone's abandoned pet, and you should indeed "rescue" him. Take thelittle squirt to the vet--it's probably got fleas, mitesetc.from running around, and the vet can tell you if it's a he or a she.
If he is wild, don't worry about him surviving. He'll be just fine.I've seen many wild babies grow up, and they can take care ofthemselves better than you can.
Best of luck! I hope for your sake it's not wild, because pet bunnies are awesome and you'll have fun with it!
Rose