Apparently about a week ago, a bunch of human rights workers, journalists from 11 countries, and a a former US congresswoman (Cynthia McKinney) were en route to Gaza with humanitarian supplies, but were halted and imprisoned by the Israeli navy. Juan Cole has more. Also see here.
It seems the point of this exercise is classic nonviolent resistance, MLK-style. You attempt to provoke a violent, disproportionate response from the oppressors to sway moderate opinion in your direction. In this case, though, the response of the media is crucial, and in this case I haven't seen a single story from a major US outlet. Currently an American Idol retrospective is on my television, which is clearly more important than a humanitarian crisis perpetrated by an blockade in obvious violation of the Geneva Conventions.