I am sorry to name other editor as an example.
but if you guys had a chance to try TextMate under OSX, it is such an example for this.

the idea, is most of the time you press '(' you'll eventually press ')'
so why the editor is not doing it for me output '()' when I simply press '(' and placing the cursor in the middle.

same for [, {, ', and "

also, something sweet is to be able to surround a selection by pressing the left one

like i write

if var == true

and then I want to get 

if (var == true)

I could just select 'var == true' and press '(' 

not sure If i'm clear.

i actually wrote a small patch for KDE katepart

http://bugs.kde.org/show_bug.cgi?id=101213

nothing complicated though, ....