At the time of writing, the following resrouces on Pega Community and Pega Academy are the best ways to get up to speed with Pega Infinity's latest feature set:
Product by Product knowledge base on Pega Community, starting with the All Products page
What's New videos from the Pega Community Video Library where Pega's Product Managers walk through the key features introduced in their product space. Each minor release of Pega Infinity has videos covering the major product areas, although the video series goes as far back as Pega 7.1.6.
Get yourself "Current" in Pega Academy by reviewing the latest versions of these Missions that make reference to Pega Infinity capabilities