trakkerguy - 1:25 am on Jul 14, 2011 (gmt 0)
The HubPages subdomain testing began in late June and already has shown positive results
I thought that sounded a bit quick to be the reason myself - at first. But it actually makes sense, imo.
Being a NEW subdomain, it starts with a CLEAN SLATE.
So, the pages on that subdomain start to rank soon after discovered. Kinda like a penalty was removed. Sorry, I know the "penalty" issue is a can of worms...