Unfortunately, this one seems to have stepped out of the net rumor fog and become fact.
According to Zap2it.com, an unnamed Fox Network spokeswoman confirmed the network is canceling FUTURAMA.
Here's the quote: "FOX has decided not to order more episodes at this time, but we may do so in the future."
According to his interview with CINESCAPE magazine, executive producer David X. Cohen, the network has 28 episodes backlogged. That's enough to finish this season and half of next season.
According to the spokeswoman, Fox will burn them off in just that fashion. More on this as it comes.