The @NASA sponsored @NASATweetup held at the iconic countdown clock at the press site:
@NASATweetup/sts-135-launch

Space View Park Tweetup:
@SVPTweetup

NASA Causeway:
@CausewayTweetup/sts135-causewaytweetup

Follow the @NASA_Astronauts #FinalFour: @Astro_Ferg @Astro_Doug @Astro_Sandy @Astro_Rex