The Emmys on Fox usually get the lowest ratings (available in less homes, the Fox audience isn't interested in Emmys) so no comedian wants to host the show and then have a poor showing ratings wise. If you check the last time Fox had the Emmys they didn't have a host they had about 8 comedians (some who had hosted in the past and were essentially presenters but just extended for comedy) as their host. So once again Fox can't get anyone and Ryan Seacrest never says no.
If you've seen Knocked Up you know they guy can do comedy but that kind won't end up at the Emmys. Prepare for the American Idol references. The thing is this is the guy whose on the red carpet for these events.
I believe its ABC, CBS and then NBC. So Conan will be back in 2010. Probably.