*Forum Update - Now with real First and Last Names!* - Please Read
I upgraded to the newest version of Vanilla tonight and I also activated a new plugin that provides actual First/Last name functionality. You'll notice that everyones posts are missing the header name by their picture, you need to click your username up at the top of the forum and go to 'Edit My Account' in that popup you'll see new First Name and Last Name boxes. Populate the new boxes with your proper name and it will display on your posts.
A little version of your actual username will display below it prepended with the @ sign. If you want to @ someone you need to use their actual username, fortunately if you click their @ username it will auto populate it in the reply box at the bottom of the page .
New folks should be pointed to the 'Edit My Account' popup to fill out their real names.