I never knew Steve Jobs, but he's always been a part of my life—from the Apple IIe on which I learned to program BASIC three decades ago, to the iPad on which I'm typing this post, and all the life-altering products I've owned in between. And, while my kids don't know it, he's been an important part of their lives too, through the wonderful characters he made possible with Pixar.
I have little to add to what others have already eloquently said. The world has lost a great visionary—our generation's Edison—whose impact will be felt for years to come, yet whose import will not fully be known for centuries. Instead of imparting some great words of wisdom, I'll let Steve speak for himself, via his 2005 Stanford commencement address, given shortly after his cancer diagnosis.
Rest in peace. Heaven will be a cooler place with you there.