I don't see the sub domain solution being a long term one.
As indyank says, hubpages haven't addressed the underlying issue of quality which means spammers can replicate this idea with a scatter gun approach to content and just see what Google likes. Eventually I see Google adjusting to this tactic and treating sub domain content as part of the main domain's content and hitting the lot if low quality content is found.
It's a short term workaround. Unless the underlying issue is addressed it's just a matter of time before you will be hit again, IMO.