Starting tomorrow (9/2/12), Rite Aid is rolling out their Load2Card program nationwide.
Basically, +UP Rewards will automatically load to your Wellness+ card rather than printing on the bottom of your receipt. Each +UP Reward can then be used starting at 6 am the following day and will be valid for 14 days.
You will have the option of sticking with the paper +UP Rewards by asking the cashier at Rite Aid to switch you to the paper +UP option, but you still can't use the +UP Rewards until 6 am the following day, making it impossible to immediately roll +UP Rewards.
According to the Load2Card FAQ, the system will redeem the highest value +UP Rewards first (rather than those that expire first). It looks like you will be able to manage your +UP Rewards via computer or smartphone to try to ensure that the correct +UP Rewards get spent, but it seems rather complicated.