There are many message boards (including this one) where emoticons will automaticlaly be converted from your text into a nice gif - In which case surely it makes sense for you to close your outer brackets resulting in:
According to H W Fowler's The King's English, II Edition, Part I, Chapter III Airs and Graces, Section "Conveying that Sentiment",
The arrangement of the emoticons depends, in large part, whither the writing is intended to be published, and how the final form of the text would manifest. If there be a conversion, an automatic one by means of certain computing functions, of the emoticonal parenthetical expressions, into little images representing them, one may include, consciously, the closing parenthesis, in addition to the one intended to be taken up by the image-converter. Else, a single closing parenthesis would suffice.
I usually just use a different kind of parenthesis to make things clearer. Granted, they aren't really parens, but it is still clear what is going on. I agree with everyone above that the space helps too.
And we are techies. We can come up with many kinds of parens/surrounding marks