yes this rescue neuters kittens before they go off to their new homes, they have to be the right weight though, but I can't remember what the weight is now.
I must admit I hadn't heard of early neutering, but I have fostered lots of kittens for this rescue and have another now, and I must admit they do bounce back very quickly and you wouldn't even know they had had surgery running around climbing and jumping about just hours after lol
More and more of the rescues that we work with are now early neutering in a bid to try and help the cat situation.