Also, FYI: I finally remembered to write out the rule about not posting confidential information: http://sdcfans.com/forums/index.php?topic=3.msg3#msg3
You need to define better what is considered a leak and what is considered in the public realm. If they file a name for trademark, is that considered "postable"? If they file construction permits and have a layout of the ride, is that considered "postable"? If another site breaks the news and posts a leak are we to ignore it and pretend it doesn't exist or is that considered "postable"? Deciding now how you want to proceed will help you in the future - especially with larger projects on the horizon.
Trademark filings fall into a grey area... but I think it's public enough that no one can hold it against us if we point it out. It's become par for the course with enthusiast communities anyway.
While still in the same grey area, I feel like anything publicly filed that has a layout picture in it that hasn't been announced yet shouldn't be posted. That's never been an issue yet though.
The main thing I want to avoid is a leak such as what happened in 2012 with the Outlaw Run announcement that was spoiled because HFEC's website team didn't know what they were doing. While it was their fault and it quickly exploded onto other forums, it was posted here first, and it gave us a bad reputation. If it happens again, I think we should cater to the park's wishes and pretend we don't see it.
Basically: don't give it away! A lot of this we have to play by ear because it's different every year. We usually narrow down what's going to be announced pretty closely by the time it's announced, but we do it through the natural progression of spotting clues and following rumors.