I would say it depends on what type of batting you're using. I used to use Mountain Mist Light Batting, which is polyester. I would just lay it out on a bed for a day or two to ease the wrinkles. (One time I put it in the dryer on very low heat to speed up the process and it really fluffed up the batting - big mistake!)
For the last several years I've been using Hobbs Heirloom 80/20 and I do presoak it then dry it on low heat. It relaxes the folds and wrinkles and shrinks it down some since I don't like a lot of shrinkage and puckering on my finished quilts. If you do like the puckered look on your finished quilts, then either lay it out on a spare bed for a day or two or as suggested above, throw in the dryer with a damp towel to help it relax. (doing this will still shrink it some, but not as much as it would if you did the presoak first.)
Hope this helps some!
