Twitter blocked #occupywallst from trending; people switched to #takewallstreet and it was trending again.
I don't see any really good reason to think of yahoo or internet in the USA as some bastion of freedom; especially when it can be 'blocked' by such murky means as a spam filter (plausible deniability allows people to act out just a bit more).
Our government has shown again and again that it is willing to tap all our means of communication (to the point of potential constitutional infringement) and mega corps have been generally willing participants.
To dismiss some phrase or website being manually dropped into a spam filter as an outrageous conspiracy theory makes me wonder if I am insane; because it's my perception these mega corps, banks, and government agencies will go to whatever extreme they can get away with; rather than up to some arbitrary point of what is 'right or wrong'; and this certainly seems like something they can get away with.