YourFriendlyGamer, the reason they ask for your PayPal detailes is for your Hubpage ad earnings. You get adesnse ads on all of your pages which you can earn from, that money will come in a cheque or direct to your bacnk account, depends on how your adsense settings are done.
You also get a hubpages ad on every one of your hubs, it looks no diffrent to a adsense ad, this is why you supply paypal. Hubpages pay you for the amount of impressions you get from their adds. Its not a scam or anything it's just another way to earn money here.