Twitter announced last Friday that all 100 members of the Senate as well as 90% (398 members) of the House of Representatives are on Twitter. In the 112th Congress only 44% of Senators were on Twitter. House use of Twitter has also increased from 35% to 90% (398 representatives). Twitter also announced that Michelle Obama will be tweeting from @FLOTUS  about her life as First Lady.
Raw numbers can be misleading where Twitter is concerned. The federal tech sphere alone is littered with rarely used Twitter accounts. The Senate’s story seems different, though.
A quick review of about 30 senators’ handles revealed no slackers. All of the senators -- or usually their staffs, of course -- are tweeting at least several times a week but, more importantly, a solid proportion of those tweets include content that would actually be valuable to people following the senators’ activities, such as links to legislation the lawmaker introduced, notes on committee work and alerts about media appearances.