It's been 1 month since I've started incorporating 10,000 steps into my day, and I am happy to report that I'm feeling great! My energy level has gone up, I feel fleet-footed, my posture has improved, and yesterday I discovered that I'd lost 4 pounds. That sounds about right because you should be losing about 1 pound per week (remember, you need to burn off 3500 excess calories to lose 1 pound), but that's honestly just a side to the overall emotional/physical feeling of well-being.
Here's some good information about walking.
I feel like a little pixie!