Live coverage that is. No Dateline or 20/20 specials. Here in the US, we can watch the wedding through live streaming: http://www.mariageprincier-live.com/
UPDATE: I CLICKED ON THE LINK AND GOT A MESSAGE STATING THAT THE CIVIL CEREMONY COVERAGE IS RESTRICTED TO MONACO TERRITORY.
CNN.com will have live streaming. Euronews, a cable news channel from Europe, will have live coverage on Saturday.
Yes, there will be coverage on the evening news, and on the 24 hour news channels, but, as far as I know, none of the news networks have purchased the rights to the wedding.
However, channel surfing is recommended. It is entirely possible that one of the news networks, CNN, CNNI, MSNBC or FAUX News (also known as Fox) might break in to show parts of the ceremonies.