Ideal isn't even available on Typekit. HFJ is fussy about webfonts.
According to Jason Kottke HFJ has their own webfonts service in private beta. He's using their Whitney font with this new service in his redesigned site:
Frere-Jones (I think it was him?) recently gave a talk about HFJ's web font strategy. My understanding is that it's going to be idiosyncratic.
Whoops, my (really) bad! I don't know why I remembered this incorrectly. Google web fonts has Open Sans--not bad by Google web fonts standards, but no ideal sans. http://www.google.com/webfonts/specimen/Open+Sans