An intriguing sign of the times: Discovery is expected to announce today that it’s rebranding Discovery Home as an eco-friendly channel all about environmental consciousness. According to Broadcasting & Cable, the move is part of Discovery’s PlanetGreen initiative, which is about “celebrating, preserving and protecting the planet” (in the words of Discovery CEO David Zaslav). In addition to the network rebrand, coming in 2008, the initiative will include green-focused Web content and sites, as well as environmental programming on Discovery Communications’ other networks. Somewhere, Al Gore is smiling.