I figured this would be more appropriate here than mechanics, since everyone here (well, most..) know about mountain biking features.

My new avid juicy 7 needed bleeding. Note: needed. I did what I heard before; pumped the lever for a minute. Now it works fine! Couple questions -

a. Why does pumping the brake lever work as bleeding the brake?

b. Is "bleeding" the brake via pumping the lever a long lasting treatement? Will I go out tommorow to find that my front brake doesn't work up to it's potential?

Thanks for your help!