Yes you can make a quilt using a serger. Eleanor Burn's used a serger on some of her earlier shows. Nancy Ziemen fron Sewing with Nancy uses a serger for a lot of her quilts.
Check out The Quilt Show website, click on Bernina videoes in the upper left corner,then click on One Step Quilting. They show how to make a reversible quilt. In the video they are making a bookcover, but, the method can be used to make a quilt as well. A serger will work for large,less complicated patterns. I wouldn't use a serger on say a difficult block but for something simple like a Irish Chain, a Nine Patch etc it would work fine. The thing is, if you have a serger I would use it for some quilt patterns. If however you don't have one, I wouldn't go to the expense of buying one just for quilting. If you plan on making garments or home dec, a serger is wonderful. Also, it makes making a fleece blanket, a snap! It just depends on what you intend to create.