There are a number of websites you could use to trade in your old phones for cash, such as Gazelleand even Apple. However, these sites require you to answer questions, and send in your device through the mail. It may take some time before you see any money for your old phone. Meanwhile, you're without a phone. Apple is now looking to bring their trade-in program into their retail stores. This means someone could go into an Apple Store, give them their old phone, and get credit they can use for a new one. The credit isn't as much as someone could get through Gazelle, but you pay for convenience.
With the new iPhone 5S, iPhone 5C, and new iPad coming out this fall, now could be the perfect time for Apple to start this program. If the rumors are correct, the trade in program will start before Apple reveals their new products early next month. It's even possible that the program could start as early as the end of this month.