Left and right gutters on main grid

[bongoman]

I'm used to 960.gs grid which gives a gutter on the left and right of the 
main grid which allows for the outer columns to have some whitespace when 
set off against the main container/wrapper.

I'm struggling to set this up in Bootstrap - so for instance, if I want a 
three column layout I have:

<div class="container">
>   <div class="row">
>     <div class="span4">
>     </div>
>     <div class="span4">
>     </div>
>     <div class="span4">
>     </div>
>   </div>
> </div>
>

Then my outermost columns are butted up against the side of the container 
div with no gutter. Ideally I'd want an equal gutter on the outside of the 
outermost spans matching the  internal spacing between the span4 divs.

Any clues appreciated....