This is a manually updated list of people twittering about the israeli massacre  on a civilian aid ship headed for Gaza

Note: please comment if you miss anybody/anything here.

Twitter accounts updated within the last hour:
Sarabughazal – Tweets from Beirut
ielsakka – Tweets from Kairo
AmirAlx – Tweets about it
Rosah81 – Tweets about it
thecatwithfish – Tweets about it
uruknet – Tweets about it
hinstance – Tweets about it

Twitter accounts updated within the last three hours:
Tarjem – Tweets about it
Omar_Gaza – Tweets about it

Twitter accounts updated later
7iber – Tweets about it, focus on pictures
35east – Tweets about it

Hashtags
#flotilla (Appears to be cencored by Twitter?)
#freedomflotilla

Other resources
The Guardian have a live blog about the event as it unfolds.