It would be nice to see it again soon, considering that it seemed to be one of the Queen Mother's favorites, having been worn to many State and family events.
Besides William's christening as posted by Nellie above, here are a few more:
Posing with the King and Princess Margaret
Welcoming Juliana and Bernhard for a state visit
Visiting the White House, where it was eyed by Mamie Eisenhower
80th birthday celebrations
Andrew and Sarah's wedding (I have a better pic somewhere)
90th birthday
Edward and Sophie's wedding (Where she recycled her 80th birthday hat)