Put in your Zip Code on this page and do a search and you may be surprised by the responses when you call.
There are 2 stores within 35 miles of my location and I called both...
Store #1 said: We will have them on display, I can't say if we will be selling them. I asked "Should I call back Saturday?" And he said "Just stop on in".
I'm taking that as a "Yes" they will have them.
Store #2 said: Yes, we will have them for sale and be open at 9:00AM.
Between the normal Apple stores, the Best Buy stores, and now these smaller stores (that many people probably don't even know about), it should be highly likely to get your hands on an iPad on Saturday if you did not preorder...or even if you did, maybe smaller lines here.