I feel if you are using quilt shop quality fabrics from the same manufacturer, it is fine to skip the pre-washing. fabric will cut and stitch more accurately with the sizing in it and also if you add more starch or sizing before you begin your project. (I use mary ellen's best press and love it but there has been a lot of discussion about various starch products on the digest, so check through older posts). If a fabric is going to shrink, you will see it happen before your eyes under the iron if you have sprayed it with sizing before the pressing.
If you really suspect a color is unstable, I would check it by rinsing a small swatch under tepid water and allowing it to dry on a white paper towel. No color transfer, you are ok, if there is, then wash until it does not run, or use something like retayne to set color.
I almost always wash my quilts after quilting, so the sizing is rinsed out. When I wash them, I use cold water, and no soap, just rinse and spin and dry. That gives my quilts more of a vintage look b/c I use cotton batting.
I would *not* dry clean quilts, no reason to expose the fabrics to chemicals, and I don't think you would want a baby next to them either. Baby quilts will usually be washed quite a bit, so I think you need to wash it before giving, just to make sure you are good to go.
If you are using assorted scraps of fabric from all over the place, or lesser quality, then I think you need to pre-wash. chain stores often receive test runs and seconds and the colors are not as stable as the bolts sent to the quilt shops, even though they may look the same. This is why you will sometimes see the color rubbing off onto your sewing machine bed from the chain store fabrics, and it does not happen with the same collection from the quilt shop.
Hope this helps!