On TV: Tune to NBC (or CBS)
The peacock's got sole rights to the live broadcast this year, so if you've got cable/a digital TV antenna, tune to your local NBC affiliate to catch the whole show from 9am to 12pm EST.
Update: It looks like NBC just has the rights to the live broadcast in front of Macy's. CBS, meanwhile, is actually broadcasting from further up the parade route near Central Park, although they're ALSO declaring you'll only see the parade on their channel.
On the Internet: NBC's website
If you're not near a TV, you can also tap into the feed online by heading to NBC's site. There's one catch, though: you'll need a cable login to access the video, because there's no escaping the clutches of cable.