This update enables sandboxing for OS X Lion and improves overall stability.
This is the very first app I’ve heard of that implements sandboxing.
According to Apple, “sandboxing protects the system by limiting the kinds of things an application can do, such as accessing files on disk or resources over the network. Limiting the capabilities of an app to just those operations that it needs to perform helps keep the rest of the system more secure in the event that an app is compromised.”
Not a big surprise to see the Pixelmator team ahead of the curve on implementing new features.