Tales from the Smart Client : The History of Sparkle: Year One: "The name of the product I work on is Microsoft Expression Code Named 'Interactive Designer/Sparkle'. This is not the final name.
For four years it has internally been known as Sparkle. So for a history of the product, I'll use that name.
I wasn't around for the start of Sparkle. The people who know the very origins of the product are either gone or very, very busy...but this is what have been able to reconstruct."
See the full post for Sparkle history.