Tracking Query Plan Changes

I was reading a blog post from Brent Ozar (SQL Server Query Store), which detailed Microsoft's announced future feature in SQL Server that aims to store a history of cached execution plans. The main purpose, it seems, of such a feature is to aid in performance troubleshooting and tuning. If something has changed recently and a query or store procedure begins behaving badly, there will be another tool in the DBA toolbelt to aid in finding what happened. Beyond that I'll let others explain it further.