The main PHP.net site has a post with some unfortunate news about the Windows PECL repository:

Due to unfortunate circumstances Windows binaries for PECL extensions will no longer be available on http://pecl4win.php.net. Work is being done to incorporate Windows binaries for PECL extensions into pecl.php.net and will hopefully be ready early 2009.

If you are interested in helping out on the project, join up on PHP Windows Development mailing list.