I can confirm Frank's note (made 1 year ago, see below) about requirement of "libsasl.dll" library. I have "PHP Version 5.4.7" and my Apache fails to restart with error saying, that "libsasl.dll" is missing, once I enable php_ldap.dll extension in PHP configuration.
What is even more strange, I DO HAVE this library (along with required "ssleay32.dll" and "libeay32.dll" in my PHP's directory and my PHP's directory IS listed in Windows' PATH variable and even so, I'm facing the problem of Apache failing to start.
The only workaround, I found is to copy "libsasl.dll" to "system32" system directory. Solution, that PHP documentation here discourages.
So, to summarize, section "Note to Win32 users" is twice wrong. You DO have to have "libsasl.dll" directory and you have to place it in your system folder.