LOS ANGELES (Hollywood Reporter) - Could "green" become a new watchword in TV programming? While the media companies have long been touting everything they're doing behind the scenes to become more environment-friendly, the message increasingly is seeping into their programming. On Wednesday, Discovery Communications launches the first 24/7 eco-friendly network, Planet Green, which will take over the space occupied by Discovery Home Channel. That follows NBC Universal's second companywide "Green Week" in April -- featuring 100 hours of green-themed content airing across 42 NBC Universal brands and 28 Web sites -- with two more already planned for November and April....