[WovenTales]

There's an article I keep in my bookmarks for times like this: http://www.heracliteanriver.com/?p=324

In short, wider sentence spacing goes back to the first English standards of the eighteenth century – including the first nine editions of the Chicago Manual of Style, and even the tenth still had it as an en-space – and only really started falling out of favour in the twenties. Typewriters had limited effect, but the automated typesetters that suceeded them were actually what killed it off, to simplify the programming.

I typically do still type a single space, but I take full advantage of my preferred TeX flavour's (ConTeXt) automatic conversion to wider spaces. One successful, post-education convert here!