Well, it's official '" the phpBB package has been finished, tested and accepted into the Web Application Gallery. You can see the official announcement on the Microsoft Web Platform blog. That means that you can install phpBB on Windows through the Web Platform Installer (WebPI) which gives you a very simple wizard to walk through.
With the Platform Installer, handling most of the dependencies is all done for you and installing this very popular application onto your site or local machine is just a few clicks away. This phpBB install requires that you use PHP 5.2.13 and SQL Server. This package was pulled together by a group at the JumpIn Camp that happened recently.