css3 is

Many exciting new functions and features are being thought up for CSS3. We will try and showcase some of them on this page, when they get implemented in either Fire fox, Konqueror, Opera or Safari/Web-kit,Borders
* border-color
* border-image
* border-radius
* box-shadow
* background-origin and background-clip
* background-size
* multiple backgrounds
* HSL colors
* HSLA colors
* opacity
* RGBA colors
Text effects
* text-shadow
* text-overflow
* word-wrap
Here all about a css you get a idea of that.

... not implemented in any browser

That's the problem with this stuff. There may be some great feature that I might want to use, but the reality is that even if it is implemented, many people will be looking at it with older browsers and will never see it. Worse yet, if you make a new feature such as corner radius a integral part of the design,it won't look as you intended it to look on many computers.

Then there are the IE browsers that interpret CSS the MS way...
I just use core CSS that is understood by most browsers.