Actually, PHP has several real frameworks available for it. One of the more interesting ones is greenorange which is a framework and an IDE via web interface all rolled into one.
I would actually say that php can be used to build its own framework, but PHP in and of itself is kinda a half-framework, considering all the external packages it can incorporate, like libdb, url wrappers, ldap interface, PDO db interface etc...
But a framework generally includes larger things like form builders and such.