Logic Pro was the last Apple's Mac app that still hadn't been in the Mac App Store until now.
Logic Express was ditched, Soundtrack Pro was also ditched, Mainstage was separated from the package and Logic Pro is now at a new low price point of $199 in the Mac App Store.
Awesome! It's still a version 9 though. I'm sure will witness a release of Logic Pro X within a year's time.
Release notes for Logic Pro 9.1.6 can be found here.