I was sentimentally attached to the name "Infocard", as I was to "Indigo" and "Avalon"... but I've to say that I love the name CardSpace! The acronym (WCS) sounds even familiar, now that I have learned to pronounce all those W-consonant-consonant. [:)]
Check out the announcement of the new name on Somasegar blog.
Ah, I was almost forgetting (just kidding of course): the entire WinFx has changed name, and from now on it will be known as the .NET Framework 3.0.