It's good for one time redemption per household.
Shipping will add $7.49 TO YOUR TOTAL.
So basically you'll be paying 7 cents a print.
Here are the terms:
101 free 4x6 prints
Offer is for 101 free 4x6 prints for Shutterfly customers only. To receive these, customer must place an order for 101 4x6 prints by July 6, 2012 (11:59 PM) Pacific Standard Time. Customer must then enter a reward code at checkout to receive the offer. Taxes, shipping and handling will apply. Offer valid for shipped orders only. Not valid on other print sizes except for 4x6 prints. Offer limited to 101 free 4x6 prints and valid for one-time redemption per billing address. Customers may order additional prints and products in the same order at their own expense. The itemized discount will be shown on the Review Order page prior to checkout. No minimum purchase requirement applies. Offer value may not be transferred or redeemed for any value other than stated. This discount only applies to orders placed after signing in to a Shutterfly account through www.shutterfly.com. Orders placed through Shutterfly Pro Galleries, Microsoft's Online Print Wizard, and anonymous orders placed through Shutterfly's online share system are not eligible for the discount.
Compliance:
Failure to comply with the terms and conditions of this offer will result in repayment to Shutterfly for all related expenses including but not limited to the retail value of products ordered, administrative costs, and legal fees.
Participants may either upload JPEG images (scanned or from a digital camera); or use pictures shared by friends through the Shutterfly sharing system. A compatible web browser is required: Internet Explorer 6.0+ (Windows only); Netscape Navigator 7.0+; FireFox 1.5+; Safari 1.2+; or AOL 5.0+.
Shutterfly reserves the right to cancel or suspend this offer at any time.