You don't need a special TV to get IPTV. You're talking about services such as U-Verse, right? They go through a converter and then plug into your TV with an HDMI or component jacks.
If you're talking about a TV that can connect to the web via RJ45, that's different. I personally don't need/want one yet because my DVD player AND Roku box both connect to the internet. So, it's basically like my TV does anyways. I also haven't switched over to U-Verse yet because they're still more expensive than Comcast for the same (albeit not as fancy) services.