Firefox 7 and WebGL

One of the advantages of upgrading my firefox browser to version 7 is the enhanced 3D acceleration for certain video cards, in my case an AMD 890GX Integrated graphics chipset on the motherboard (Radeon HD 4290 equivalent). In prior versions of Firefox, my driver, the free and open source radeon driver was blacklisted for GPU accelerated windows and WebGL. So after upgrading to version 7.0.1 of Firefox, I checked under Help | Troubleshooting Information and was surprised to see this:

So I entered aboug:config in the address box and searched on webgl. I found a parameter webgl.disabled set to true. I'm not sure how this got set to true, but changing it to false solved the problem. Now I can enjoy WebGL websites like this one.