They don't have one no more. that's the whole point...
:)
http://www.thestreet.com/_yahoo/newsanalysis/wallstreet/10317303.html?cm_ven=YAHOO&cm_cat=FREE&cm_ite=NA
IMO you are just doubling up a rev cal. and if the underlying doesn't move significantly, you will be doubling up your losses. try to re-model your holy grail :)
Actually, i was wondering that myself. long holidays season, maybe? I've been long vega positions on YHOO and DNA for 2 weeks now, and - nothing (yet?). vols graph flat as the sea of some dream-island. and in the meantime, theta is eating me alive.