The third level of CSS theoretically should allow to implement lots and lots of features on websites in a simple yet effective way. For example - multiple backgrounds, stretched backgrounds, rounded corners for website elements etc. There certainly is a difference between writing complex hacks in order to achieve some rather simple visual element and a regularly written expression allowing the same effect.
However I should be much more naive than I am to believe that CSS 3.0 will become a respected standard in the years to come. First, currently the main player in the browser market - the godforsaken IE - still isn`t even CSS 2 compliant, and only the upcoming 8th version of this browser should theoretically catch up with those standards. Then there`s the very long procedure of developing the CSS 3.0 requirements, and there doesn`t seem to be an end for it. There also could be a solution of introducing CSS 2.5 which would include some of the new "features" which would be most desireable and least difficult to implement.
The strange thing is that some browsers already have impelemented a few of the CSS 3.0 features. For example, if you read by webpage on a new version of Safari or Firefox you can notice that the INPUT fields and also the main window have rounded corners - that is done by using specific CSS properties available in these browsers. Meanwhile if you use Opera with a speech plugin installed, you can listen to this article by selecting the text, pressing the right mouse button and the selecting "speak". You should be able to hear a synthesized woman`s voice.
If the "alternative" browsers like Firefox, Opera, Safari were able to take away the leading role in web browsers from the standard-hating Internet Explorer, I think the issue would get a strong push forwards. Currently, according to data from Marketshare, IE holds about 75% of the market, Firefox - 18%, Safari - 6% and Opera - less than 1%. If IE were to drop to around 50%, we might have a chance.