Social media is the area for search engine optimization companies to get traffic and linking. Most of the SEO packages in these days including submission to social media sites like face book, digg, 10URL, twitter and many more known as social bookmarking submission services
I think this new field of social media optimization is getting importance day by day and you can get lot of traffic and branding by submitting your articles, news, press release or announcement of products to social media sites.
Beyond all it is important to choose a good social bookmarking service company which can submit your site or article to quality social bookmarking sites. Only good submission company helps you in getting good approval or inbound links for your site