http://www.p22.com/lanston/products/spacing_sorts.html
I’m with Anil on this one: year-on-year, the tech world’s April Fool efforts are pretty dismal. (Google’s effort is particularly leaden—see the tour.) P22’s contribution is a a font of “spacing sorts,” (in metal, retailed for $10 in 1912!) which not only actually exists (“order” it), but includes the full set of Unicode spacing characters.