Thanks to you both for the replies.
If I run Firefox (3.6.18) from the terminal and try a webgl demo page the page shows an error saying I don't have webgl in my browser. I do not see any log in the working directory.
I am not really sure if I need webgl because it looks like it is for 3D effects - I don't want 3D, I just want to use GPU acceleration to help render animated 2D effects like transitions and text animation (scrolling).
Is there a pre-built Firefox 4 for this platform, or do I have to build it from source? Has anyone done this and made it work?