"Headings" selector?

It's not uncommon to see…

    h1, h2, h3, h4, h5, h6 { font-weight: bold; }

Yesterday I was forced to write…

    #preview h1, #preview h2, #preview h3, #preview h4, #preview
h5, #preview h6 { /* rules */ }

It'd be great to be able to write…

    h { font-weight: bold; }

and…

    #preview h { /* rules */ }

I don't know how difficult this'd be to implement, but I do know that I'm
not the only one who'd find it useful. :)

David