Stippling is any microquilting design that is densely spaced and adds texture. It is not necessarily a meander type pattern.
http://quilting.about.com/od/quiltin...lequilting.htm
Over time the two terms somehow became synonomous but stippling is really very different from meander.
Stippling is commonly associated with handquilting, usually wholecloth welsh type designs. Here is a link to a prime example of stippling posted by Andrea (Borntohandquilt). Note the second picture in the below link. In the very center medallion, where the diamond points meet... The dense background quilting that seems to have no distinct patter but makes those diamonds just pop up off the surface of the quilt, that is stippling.
http://www.quiltingboard.com/picture...t-t177631.html
Here is another AMAZING example of Andrea's hand stippling (scroll to the middle of the first page to see the picture she posted)
http://www.quiltingboard.com/main-f1...g-t158538.html
In machine and LAQ it can be any very dense background design but most commonly used is a very small micro meander, most likely because it is easy to do as a continuous quilting line which is probably how the two terms got innappropriately interchanged. Here is another great blog that visually shows the difference with a picture
http://www.quilting-tidbits.com/mach...g-designs.html