CBS (www.cbsnews.com) = Front-page tab for SciTech (heavy on tech, but science is there)
Fox news = Front-page Science tab, with separate Health and Technology and a lot of content in specialty areas like paleontology
NBC news = separate Science, Tech, and Health tabs, plus they have the marvelous Alan Boyle's Cosmic Log
MSNBC = can't find anything at all besides consumer tech and health.
ABC news = natural science stories are hidden under the Tech tab.
So using ease of access to science stories as the only criterion, Fox, and NBC get As, CBS a B, ABC gets a C, and CNN and MSNBC get Fs.