I don't know. A lot of the smart PHP developers are still there. Maybe people using PHP moved on, but PHP devs are still strong.
As for PHP code, pear is still widely used for code distribution. Combined with pecl, and you have two resources for code distribution depending on how the code is integrated (PHP or C). And don't confuse pear as a library. It's a distribution method. For example, PHPUnit is installed via pear.