Contrary to what we previously heard, Hulu Plus for the PS3 will not require a Playstation Plus subscription forever. A Playstation Plus subscription is only required during the current Hulu Plus "preview period".
According to Hulu Support:
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.
We're not sure when the "preview period" officially ends (or how far along it is for the public), but it's sort of comforting to know we won't have to spring $50/year for the not-exactly-necessary Playstation Plus subscription to get our Hulu on. But misers beware, you'll still need the $10/month Hulu subscription. [Reddit via Engadget]