In 6.1.4 it's in the modules folder. Whether it works or not is another question. I know for a fact that the Vbulletin (vbull.aemod) is absolutely useless.
They actually had vbulletin integration listed as a feature for Dolphin but it eventually disappeared from the list, I wouldn't be suprised if the same happened for phpbb.
DO NOT USE THE MODULES FOLDER TO INTEGRATE PHPBB3 INTO A SITE. HOW BAD DO YOU WANT TO SCREW UP HIS SITE GIVING OUT THAT KIND OF INFORMATION?
THOSE MODULES DO NOT WORK AND HAVE NOT BEEN SUPPORTED BY BOONEX IN A LONG TIME, THEY SIMPLY HAVE NOT REMOVED THEM FROM THE ADMIN PANEL.
Now, if your looking to integrate, hop over to expertzzz.com and look for eSASe at this link:
http://www.expertzzz.com/Downloadz/view/3667
His integration package does work, and it works quite well. Once you have that installed, come back and I'll show you how to add a decent menu into phpBB3 (without I-Framing or using a ton of images) that will enable your members to bounce from the forum to the site and back again.