She was rumored for the role the other month, now it seems set - Naomi Watts will appear in "Harry Potter and the Half-Blood Prince" reports The Courier Mail.
Watts, set to give birth in a few weeks, has just signed on for the supporting role of Draco's nasty mother Narcissa Malfoy. The actress won't have to start work on the film until September.
Also joining her are smoldering hunks Joseph Fiennes and Stuart Townsend, and whilst their roles haven't been specified it's expected both will tie into the flashbacks into the history of Voldemort. It's quite possible Joseph will play either the father of or a younger version of the character his brother Ralph Fiennes portrays.
The two key new roles of Potions master Horace Slughorn and new Minister of Magic Rufus Scrimgeour have yet to be announced but both skew decidedly older than either Fiennes or Townsend.