The Private Messaging system seems to be fully functional now.  To use click on the "SOI Member Profile" link at the top right side of the website and you will see your profile information with ability to edit if needed.  On the left side you will see a "Messages" box that will allow you to see your inbox or write a new message.  In the "to" box if you know the first letter of the member name you want to message you type that in and it will drop down a list of members that begin with that letter.

You may also click on their username if they are online and showing at the bottom of any page, or in any of their posts in the forum, and it will show your their profile with a link to "send this user a message."  This will automatically fill their member name in the to box.

When you go to your "SOI Member Profile" page if you have new messages another box will appear on the left below the "Messages" box showing that you have new messages.  Click on that link and you'll go to your inbox.  You will also receive an email notification at your account email address that you have a new message waiting.  This may be turned off if you wish when you edit your Member Profile.