Anti aliasing does not seem to be working with the free version of Unity. I've created a very simple project with a cube, camera and light to demonstrate this.
Anti aliasing is set in the settings:
Edit->Project Settings->Quality
The project is built as a web player and the resulting cube is very jagged with no anti aliasing.
Here's a link to an image of the quality settings for the project and the cube's jagged lines that's produced in my web browser that I'm using here, it's the same with Chrome and IE:
And here's a link to the Unity 3D web app itself:
http://moderncoder.byethost15.com/Unity3DCube/
It seems that anti aliasing is available in the free version so what could the story be with this?