NBC pulled their content last year after Apple refused to up their price on iTunes. One year later and a failed attempt to start its own store, NBC is back.
Starting now, NBC shows including "Heroes" and "The Office" are available via iTunes for $1.99 per episode or $2.99 for the high-definition (HD) versions. Library titles will sell for 99 cents as well.
Dennis Miller summed it up best I think we this quote:
Apple's patched-up relationship with NBC is "a case of mutual need, given NBC's library and the ubiquitous presence of Apple's platform."