With very little information to go on, it looks like WordPressdotcom has taken the final leap to enter the full, managed WP hosting arena by offering its Business plan users access to a wider range of plugins and custom themes through the Calypso dashboard. This includes access to WooCommerce and forums like bbPress and BuddyPress.
Other than new-to-me WPcom staff commenting in a community forum thread and an updated support document on the differences between WordPressdotcom and WP.org, there’s no official announcement yet to verify this change in the Business plan.
Update as of half an hour after publishing this post: a more-familiar Staff member answered in the community forum thread and confirmed that this change is official. Users who already have the Business plan upgrade can get more help and information via live chat.