Quoted for truth:
"Facebook is for fun. Tweets have a short shelf life. If you're serious about managing your career, the only social site that really matters is LinkedIn. In today's job market an invitation to "join my professional network" has become more obligatory -- and more useful -- than swapping business cards and churning out résumés."
So if you aren't on LinkedIn.com, get in! (And be sure to add me as a connection!)