Answer to the Friday Whatsit for July 9, 2010
In yet another record time guess, Murph correctly identified the Friday Whatsit as a feather. It is a Blue Jay (Cyanocitta cristata) feather that I found on my patio.
Feathers are amazing things, from an engineering standpoint. Lightweight yet super strong, evolving over millenia into the beautiful and functional structures birds have today.
For more information than you will ever need about feathers, the Wikipedia Feather article is a decent place to start.