No, there is currently nothing similar to Hibernate in PHP. Doctrine 2.0 is heading in that direction, so you might want to check it out again in the 3rd quarter of '09 at the earliest.
There are 2 main reasons why something like that does not exist yet:
1) Its still unclear whether PHP is up to the task in terms of the "heaviness" of such an ORM. People already love to complain about "performance" of almost all larger PHP libraries, "lightweight" seems to be the new cool buzzword.
"WTF, i only get 15 requests/sec" with a hello world-app in symfony/cakephp/whatever?? Screw it!" Then they go on, build their "leightweight" homegrown solutions and at the end the site can be happy if it gets 10 hits a minute. Seriously, come on.
2) Language "deficits" of PHP. One of the main things needed for "transparent persistence" is a transparent way to get data in and out of the domain objects. Java ORM solutions mostly use reflection, in PHP its only now, with 5.3 ALPHA, possible to get/set private/protected properties through reflection.
There are other problems that make such a "transparent persistence" solution more difficult and potentially more "heavy" than ActiveRecord, like:
Change tracking. Hibernate/TopLink/whatever usually keep clones of all objects read from the database so they can compare them with the originals at commit time to determine the changes in the objects.
Lazy loading is also much more difficult without an ActiveRecord-style base class. There are many possible solutions here (virutal proxy, ghost, ...) but its nevertheless more difficult than just to intercept all calls in an ActiveRecord class ala get/set.
The list of reasons goes on and on. Considering these things it should be no surprise that ActiveRecord dominates the PHP scene.
We will see how Doctrine 2 works out, whether it will succeed or not, its nevertheless an interesting challenge. The significant speed bump of PHP 5.3 helps larger php libraries a lot, while "lightweight" libraries might not even notice the difference.