This article, written by a guy who lives in Kampot a week or so back, says its closed to all. http://www.khmer440.com/article.php?id=1109

At least credit the author of the article, SBruny.
'The Chairman', as he's known by his employees, is not Vietnamese. Neither is the company itself. Even though there are 1- 2 million VNese living in Cambodia (allegedly), 95% of which live in dirt poor, crappy conditions, there's no real need to bring up this old chestnut again.
Go check out the threads on ToA regarding the slow, supposed Vietnamisation of Cambodia.
OTOH, nothing is for free, eh? Not even 'liberation'.

Drove up to the Bokor park entrance this morning(denied entry). No private vehicles are allowed up the mountain. Also checked with main tour company in Kampot and director said Bokor off limits to everyone. He believes that it will be a few months before any tourists will be allowed.