Ian Abercrombie's last major credit was as the Headmaster in Wizards of Waverly Place, which just wrapped up a few weeks ago. This is the second time in recent memory that Disney's wrapped up one of their shows, only for one of the big stars to pass away a few weeks later. The first case was with The Emperor's New School, where the show wrapped up and Eartha Kitt passed on weeks later. It's a very odd coincidence.
As JST alluded to, he also currently leaves Star Wars: The Clone Wars without a Palpatine. He was awesome in that role.
This is Xbox only. Playstation will be coming out with their own service called Vue which will basically have all of the channels Sling doesn't, basically all channels under the CBS/Viacom, Fox and NBC Universal umbrellas.