A small update to this old-ish thread:
As of yesterday, FontFont faces *are* available at MyFonts. http://typophile.com/node/102843 - and please note that their fonts were listed previously (older faces, at least), but NOTHING was actually available to buy from MyFonts. As of yesterday, the entire FF catalog is available for sale.
Also, several others referred to in this thread have signed with MyFonts in the last two years:http://www.myfonts.com/foundry/Dalton_Maag/http://www.myfonts.com/foundry/G-Type/http://www.myfonts.com/foundry/Letterhead_Fonts/
And many more are on their way, wending their way through the (recently much more stringent) foundry review process.
Hmm. One notion I can think of is to get Amazon to take up font distribution. They already market other published material. I'd think all they would have to do is give the type designers a better deal than Monotype, which shouldn't be hard.