I had a wish list book come up on 7/6. I knew we were moving at the end of July, but I thought that I had time for one more book too make it. Turns out the sender was in Alaska and the book didn't make it before we moved. Will the book be forwarded? Or will it be returned to sender?

It will be forwarded, but you will have to pay the postage. Media Mail rate does not include free forwarding. 

How far away did you move? I've heard that if you stay in the same local area, the forwarding is sometimes free.

that used to be true, but not anymore.

If it was local, we could do a handoff, just give it to the carrier at the new address, but now so many companies want the address correction, that we have to send every peice of forward mail through CFS (central forwarding system) they are the ones who put the yellow stickers on with the new address. they charge postage due on all package services-parcel post, media mail etc etc