PayPal is making some changes/upgrades, and I'm not sure if I need to make changes to my shop's settings.

Here's an excerpt from my e-mail from them. Can any of you tell if this affects our carts?

Data Center Migration

The second scheduled update includes migration to a new state-of-the-art data center in the Salt Lake City area. This data center offers new technologies and services, and was designed with a focus on reducing environmental impact. As a result of this move, new IP addresses are being introduced and you may need to make networking and/or firewall updates if you hard code IP addresses. If you are unsure of the type of authentication you are currently using or if you would like to confirm if you will be impacted by this change, we recommend contacting your web developer or IT Department regarding this notification.

For the updated list of IP addresses used by PayPal.com, please refer to the following Merchant Technical Support FAQ: IP address for PayPal servers. For the most current list of IP addresses for PayPal Sandbox services, click here: IP address for Sandbox PayPal servers. We recommend that you subscribe to these lists so you can receive automatic change notifications to the IP addresses for our servers.

https://ppmts.custhelp.com/app/answers/detail/a_id/92 is the web page describing IP changes.

Reading that, there shouldn't be any changes you need to make in the software.