Which social media is the most priority for American marketers?

In a study entitled “The 2011 State of Inbound Marketing”, HubSpot questioned American marketing professionals.
The question they were asked was the following:

“What type of social media do you consider to be the most important for your company?”

The study was published on 2 March 2011 and communicated by eMarketer. Its findings make for very interesting reading, particularly in comparison with the 2009 results:

On the way up:
►Corporate blogs remain the number one priority for 62% of professionals surveyed, an increase of 10 points in the past two years. 
►Facebook and Youtube are in joint second place with 44%, an increase of 20% and 18% respectively.
►Twitter is hot on their heels in fourth place, with a growth of 17% in two years.

On the way down:
►Digg dropped 12 points from 21% in 2009 to 9% in 2011
►Flickr lost three points, dropping from 14% to 11%
►StumbleUpon dropped sharply with a loss of 19 points, falling from 25% to 6%
►MySpace was in last place, with only 4% of marketing professionals surveyed indicating an interest in it in 2011, compared to 13% in 2009.

What's your view? Which internet marketing strategy does your company use in terms of social media?