That was probably a weather balloon. However, a couple of weeks ago, I was following a satelite wih my widefield (Orion 120mm f5) when a dim grey blur flew through my field of view, followed within 2-3 seconds by another identical object flying the same trajectory. It left me scratching my head until I identified them as Honeywell MAVs. The police deparment in our area are testing them for surveillance applications and the things are relatively silent, have no running lights, and are small enough and can fly high enough to make them look intersting as they cross your field of view.
Here is the company video:
http://www.honeywell.com/sites/portal?smap=aerospace&page=mav_video&theme=T8
Here is the company video:
http://www.honeywell.com/sites/portal?smap=aerospace&page=mav_video&theme=T8