The close of 2008 sounded the death knell for some of the most notorious spam networks on the planet. But already several new breeds of spam botnets — massive groups of hacked PCs used for spamming — have risen from the ashes, employing a mix of old and new tricks to all but ensure a steady flow of spam into e-mail boxes everywhere for many months to come. * In September, the shuttering of Northern California based host Atrivo/Intercage was the final nail in the coffin for the Storm worm, widely considered one of the most ingenious spam botnets ever created. * In November, the unplugging of Silicon Valley hosting provider McColo — a network experts say absorbed many of the refugees from Atrivo’s shutdown — spelled the beginning of the end for “Srizbi,” which was until recently considered the most massive spam botnet with an estimated 450,000 infected computers.