Well, nothing really except they use a kick a$$ social bookmarking tool. The tool was built by in-house developers and unfortunately cannot be used by anyone outside of HP (hopefully that will change some day). It’s kind of similar to the one I use but it has an animated gif, that has 4 different states displaying the icons of Stumbleupon, del.icio.us, My Yahoo and Digg rotating every few seconds.
The following is a screen shot of the tool once you click on share/tag; and you will notice all the social media channels. The cool thing is HP can add/change/delete sites in the tool and it will dynamically change it in all the blogs and web sites that use it.

I was working for HP when the HP.com web experience team spearheaded this project earlier this year; and I am glad to see that it was implemented. To see it live and in action, please visit the HP SEO blog.
Technorati Tags: social media optimization, smo, socialmediaoptimization, social bookmarking, social bookmarks, hp