Prestashop have just released a new module, "followup" which will become one of the core standard modules in Prestashop version 1.2.
The primary goal of this module is to help you increase your sales by enabling you to define rules that offer customers incentives to complete or place orders with you. There are four configurations possible;
* For each abandoned cart (not completed) - Come back and complete orders with the offer of a discount on their next order
* For each validated order placed - offer of a discount on their next order
* For each customer whose total orders reach a defined threshold - the ability to reward these custimers with a discount
* For each customer who has already ordered at least once, but has not placed new orders for a certain time - a reminder to order

For each of the above four options you can independently specify if you want to enable this feature, what discount amount you wish to apply and how long this discount is available to the customer for. The followup module uses a cron job to allow you to configure the emails that are sent when the rules are reached for customers.
Statistic are also included in this module so that you can measure the effectiveness of your emailed offers, however these statistics display for the last 30 days only.
For each type of above offer you have emailed, you can view:
* Number of e-mails sent
* Number of discount coupons used
* Conversion rate percentage

Currently Followup is in alpha release and included in the SVN updater from 21st April 2009. It is not in the packaged 1.2 alpha(1) but will be included in 1.2 alpha 2.