NBC recently issued a press release claiming that its planned coverage of the 2014 Sochi Olympics would feature the first ever prime time event coverage before the opening ceremony. However, this NBC claim is false. In 1980, ABC opened its Winter Olympics coverage in prime time on Tues 2/12 from 9:30 - 11 pm ET, one night before the opening ceremony on Wed 2/13. (For completeness, ABC did the same thing in 1984 for the Sarajevo games.)
<Update 2/25/2013: ABC also provided prime time coverage the night before the opening ceremony in 1976 for the Innsbruck games (per a blog comment which I have verified).>
I watched the Olympics on ABC that opening Tuesday in 1980 and recall the oddity of televised event coverage prior to the opening ceremony. I also found multiple newspaper archives which supported my memory. Today, I was involved in some Twitter exchanges which helped proved this claim false - Fang's Bites provided a nice summary.
I also just found video proof which further supplements this research. This ABC promo clip runs down the ABC prime time schedules including the Olympics coverage for both 2/12 and 2/13:
The ABC coverage that first night included Al Michaels and Ken Dryden calling parts of the USA-Sweden hockey game from Lake Placid. That game took place 33 years ago tomorrow.