In reply to flopsicle:
When I started running, I struggled a lot with stitches. In my case, they were mostly related to posture and to being too tense in the upper body. I spent quite a while concentrating on form and on relaxing, and they went away for the most part. A particular problem for me was hunching my shoulders. Sometimes, I still get them when I am running particularly hard, but I can usually shake them. Things that work for me to get rid of them include purposefully varying my breathing pattern, moving my arms around (I often "shake out" like I do when I am climbing), or just concentrating on relaxing my shoulders.
The other thing I found makes a difference to me is when I last ate. If I run on a completely empty stomach, or on a full stomach, I get stitches. I have a stitch-free window that lasts from about 2-4 hours after I last ate.