My biggest question as I browsed this site was: why is this useful. The first 3-4 pages I browsed, and the video I watched, didn't answer this question.
(1) get a hold of the raw data and then do cool stuff on top of it.
(2) you can contribute your own local area in a way that you want -- doesnt just have to be streets, can also be trails, riverside views etc.
(3) This is good if you're irked that Google has all the interesting street imagery that they hoard for themselves (mostly).
(4) You'd be helping openstreetmap volunteers look at your imagery when then edit the local map thus helping create our only shot at an open, fully flexible map of the world.
There's probably more, but this should be a good start. Yay, mapillary!
