Currently Being ModeratedDec 27, 2012 7:06 AM (in response to msannee)
What do you mean?
OS X machines can have 3rd party software installed and a TV tuner, if that's what you mean (or they can in the UK).
If you're in the UK you can buy a Freeview tuner for your Mac.
Currently Being ModeratedJan 1, 2013 6:35 PM (in response to msannee)
If you mean you want to display your Mac on a TV, then the answer is a qualified "yes."
For PowerPC Macs, you can use Front Row to display your movies, pictures, and DVDs in a nice, TV friendly interface similar to the first generation AppleTV. For a more glossy experience, look into XBMC. Plex is an alternative, but it generally (with some exceptions) requires an Intel processor based Mac.
You can also buy a variety of TV tuners from Elgato and other manufacturers that allow you to view (and record) a TV signal on your Mac. They plug into a USB port and connect to a TV antenna, cable line, or satellite receiver. Look into EyeTV or MythTV for controlling what channel you watch.