At around 5m/px, the imagery from planet labs doesn't currently have high enough resolution for it to be useful for tracing in OSM. It looks good only down to around z14ish.

But what they're doing is still really interesting. Their stated goal is to be able to image every part of the planet daily by the end of 2016. And it's possible in theory to process multiple passes of lower resolution imagery into a composite imagery layer with a higher effective resolution. So it wouldn't surprise me if they use their microsatellite approach to push into markets that are currently served only by hi-res imagery providers like Digital Globe (imagery from expensive satellites) and Pictometry (imagery from airplanes).

I haven't seen anything on a mailing list or anything. It would happen here:

https://github.com/osmlab/editor-layer-index