"Protesters in Iran are hailing 26-year-old Neda Soltan as a martyr after graphic videos of her apparent murder at a protest in Tehran hit the Internet. Iran experts say images of her bloody death have galvanized the country and that mourning for her — which has been banned by authorities — will bring deeper unrest."
Video of her death has been posted to YouTube but requires registration due to graphically bloody images.
Update: Via Andrew Sullivan--Borzou Daragahi compiles a superb report on Neda Agha-Soltan.