Things that are new to the installer for PHP 5.2.1:

• Support for configuring PHP as an ISAPI module.
• Support for configuring PHP for IIS 7 in CGI and ISAPI modes ( Thanks to David Wang for writing a guide on how to do it ).
• Rolling all the IIS Server options into two choices ( IIS CGI and IIS ISAPI ) where the installer will do the right thing based upon the version of Windows you have.
• Some bug fixes ( see the list )

Thanks to everyone who submitted bug reports; you should be seeing those fixes appearing in the upcoming Release Candidates for PHP 5.2.1.