Originally Posted by pdurrant
I don't think so, but it probably depends on the font.
Correct. With electronic fonts you are at the mercy of the font's kerning table, the renderer's use of that table, and the renderer's own letterspacing rules.
This latter point is generally more of an issue when justification is being applied by the renderer, either due to its own settings or instructions in the ebook itself. If the display renderer needs to space out the letters in a word, rather than just the space between words, it will space out punctuation as well as alphanumeric characters.