Well it seems there is a bit of a catch to Werdum giving Fedor an immediate rematch. Can't blame Werdum for looking for a bit of "incentive" to do this fight in October. It's also interesting that he hasn't ruled out taking another fight between the rematch with Fedor too(Overeem?).

With Fedor Emelianenko's aura of invincibility shattered, his promoter, M-1 Global, is suddenly tasked with rehabilitating Fedor's image as "the baddest man on the planet." Their best course of action starts with getting Fedor back in the cage with Fabricio Werdum as soon as possible. In their eyes, proving Fedor's loss to Werdum was a "fluke" can't come soon enough. They've already targeted October for the fight.

Fortunately for M-1, Fabricio Werdum is willing to give Fedor Emelianenko the rematch they seek, however there's a catch. According to Fighters Only, Werdum is only willing to do it on their timetable if the right incentives are provided.

 http://www.mmaconvert.com/2010/07/01/fabricio-werdum-wont-rematch-fedor-emelianenko-in-2010-without-right-incentives/

Fighters Only quotes:

Fabricio Werdum's rematch with Fedor Emelianenko will take place - but not for at least eight months, according to a source very close to the Strikeforce heavyweight. The source told Fighters Only that Werdum does not want to rematch Fedor in what remains of 2010.

.....

The source told us that Werdum has not ruled out taking another fight before rematching Fedor, and also said that he may be open to fighting him again in less than eight months if the right incentives were provided.

 http://www.fightersonlymagazine.co.uk/news/viewarticle.php?id=4799