It was originally reported last month that Hulu Plus for the PlayStation 3 would require a PlayStation Plus subscription but it turns out that only applies for the preview period. It’s unclear when said preview period will end but at least we now know that Hulu Plus on the PS3 will not require a PlayStation Plus subscription.
With the launch of Hulu Plus there have been many rumors started and we are trying our best to remedy the situation. Specifically to your question, the Playstation Plus service is only a requirement during the preview period.
Once the preview period ends you should be able to download the Hulu Plus app but that will still require the Hulu Plus subscription.