OK guys I wrote this yesterday after looking around for some suitable rounded corners code, I noticed there wasn't really a preferred way of doing it in RoR so I picked up the Rico js library and extracted the rounded corners stuff, then wrote these helpers.
I know this is Ruby-Lang but I think a lot of people are also doing RoR so there you have it. Enjoy :)
Basic how to: 1. include rico.js 2. call roundcorners somewhere on the page. ( I do it in the layout ) 3. round_div with abandon.