I snapped a photo driving home last night (yes, it was sunny in Seattle) and figured this maybe a 4G buildout tower. This has been the second tower I've seen with a crane working over a tower. I believe Seattle is in the second phase of Sprint's deployment.
I've attached a photo, how can I confirm? Go up and ask what they're working on? Look at their cell boxes?
Photo Link: http://i1265.photobucket.com/albums/jj518/drlovety/SprintTower.jpg