When you set the href of an anchor to '#', it means "go to the current
page, at the top" and so the browser will scroll to the top. When you
return false in javascript, it cancels the click action of the
hyperlink, which means when normally it would follow the link ((this
page, top)), it will not do any hyperlink action ((link-following)), so
there's no scrolling. So for those users without javascript, it
doesn't have a chance to return false ((since none of the script will
run at all)), and will "fall through" and do the hyperlink action. In
a lot of cases, an empty href will do what you're looking for ((that
is, nothing, i think, when there is no javascript available)), or
javascript:void(0), or some similar gimmick.
Hope that was vaguely enlightening.
It's early where i am though,
so i'll check back later and see if that made any sense.