If you mean for it to be used as a graphic then it's perfectly fine to sell it as an illustration. One example of which is the high rez scanned woodtype from http://www.withoutwalls.com/index.htm

Letterror used to sell it's Federal typefaces as an illustrator file that you could typeset online. And soon House Industries will offer the same old-school technique made new with an online version of the Photo-Lettering catalog.

Not sure if that could be called a typeface. It would definitely NOT be a font.

(Difference between "typeface" and "font": http://blogs.adobe.com/typblography/2005/12/quality_in_type.html)

I can't imagine there would be a (big) market for typefaces in AI.-format, but if it's anything like Ken's links, I'd for one be a potential customer ;-)

Emigre's Missionary shipped as EPS files—as well as a font—at the time when I licensed it. For some work this could be preferable.

Ken, would you please point me to a source article about House putting the photo-lettering stuff online? I'd love to read more about it.

You could search around for more but there was an article in the MAR/APR 2005 issue of Print Magazine.

http://findarticles.com/p/articles/mi_hb4324/is_200503/ai_n15074400