vb 3.0.7, and I have not done anything to the functions_bbcodeparse.php.
I figured it... the way you have your bbcode setup, is it uses the 'nonforum' settings in the bbcode functions and that case uses the "allow smileys in signature" setting. That must be enabled for the smileys to work. Easy fix would be to just add in a new case for your vbchat and point the allow/disallow to your vbchat option. Then just take out that whole check in vbchat.php and allow the bbcode functions to perfor the checks for you. Just an idea
Great mod btw ZT.