BlackBerry's tentative step into the world of feed-based social networking, BBM Channels, is at last leaving beta. As of 3PM Eastern, those with BlackBerry 10 and classic BlackBerry OS devices can use the Tumblr-like service for themselves, subscribing to content feeds from both major providers and their friends. Android and iOS users, meanwhile, will have to sit tight -- BlackBerry says that Channels support for their platforms is arriving in the "coming months."