I've just had an email about some changes to Paypal Website Payments Pro - I don't think these changes effect Zen Cart but it would be much appreciated if someone in the know could confirm. The email I received includes the below text which is the bit I'm not 100% about:

To ensure your Website Payments Pro transaction processing resumes appropriately post-migration; please check your integration and/or network configuration. If your integration and/or network configuration has hard coded PayPal’s IP addresses, please go to https://www.x.com/view-blog-post.jsp...&blogPost=4500 for more information on the new IP addresses, the planned data migration of our applications, and the scheduled migration timelines. These dates and times are subject to change, so please be sure to regularly monitor the referenced blog.