J.:
You have great responses but I wanted to add one more. I have two boys that had issues with wetting at night. My pedi recommended a company called The Potty Pager (www.pottypager.com). The pager is a SILENT alarm (yea!) that vibrates at the slightest amount of moisture. By wearing it nightly, the kids train themselves to wake up before they have an accident. Cost is about $75.00 and worth every penny.
Both of my sons did great with this device, however my older son had a relapse about the time that puberty hit (about a year later). This time I asked for meds and the pedi put him on a medication that he takes at night and it's worked wonders. He still wears the pager to bed as well but he's been dry since. I'm not that thrilled with him being on a daily medication but it's better for his self-esteem.
We also had our sons wash their sheets when they wet the bed. It wasn't a punishment, just a matter of responsibility. Plus this way they did not have to come to us and tell us. They simply took their sheets to the laundry room and started washing.
Best of luck to you and your family. Keep up the diligent good work!