My last post was really more of a lead in to this one. As I was putzing around with the configuration utility I was surprised that the Wi-Fi tab doesn't allow you to actually enter a password for a WEP or WPA/WPA2 network, which is arguably the most useful part of being able to provision a profile for wireless settings.
What I found was that although there is no password field in the GUI you can still include it with the profile by manually editing the file. The profile file that gets created is nothing more than an XML file so open it up with your favorite editor (I used Wordpad because Notepad had a tough time with the line breaks). Now somewhere between the <dict> and </dict> tags that contain the PayloadContent you need to add two more nodes:
<string>(your wireless key)</string>
I added mine directly below the SSID_STR key and string for the wireless network name. If you have multiple Wi-Fi networks you'll see a separate <dict></dict> structure for each so just make sure you put the passwords in the right spot. Now just save the file and either email or post it on a website for users to download. All they'll need to is click install to have the Wi-Fi network automatically added to their phone.