Ok hear me out. If a whale wants to announce a pump anonymously, he can make a long expensive post on
http://bitcoinmegaphone.com announcing the date and time.
If the post is long enough (ie, expensive enough) people will know he's actually a whale and is serious. Then the post's permalink will get spread around the internet, helping to ensure the pump has a good chance of happening.
Thoughts?

How much is he going to spend? 1 BTC for almost 85k characters? How rambly is he? The time it takes to write the message is not worth it lol.
LOL
CTRL+V

Seriously though, I don't think this would work. If news of the pump got too public, it would become very unpredictable.
Best way I think, would be to organise it with a bunch of other whales privately with strict timing, allowing you to play the market with people who don't have a clue what's going on...