Interactive TV - Who Uses it? Who Develops It?

bad$eed asks: "I have been in software and Internet development for 6 years. However, I have never used or seen 'Interactive TV'. It seems to be that there are a few standards around (MS WebTV, Open Digital TV, etc). Is this going to take off? I see that my bank (HSBC) now has banking through Open Digital. Who are the developers out there in the field and what tools are they using and how is it different to regular HTML content delivery? Is there a standards war going on in Interactive TV? Where does one start?"