Do you have any evidence to back up this hunch, or is this just the usual sort of unreasoned paranoia that sees third-party involvement behind any action against a disliked government?
The protests are real; the photos and video that have emerged so far are proof of that. And they have unfolded in a manner that's entirely plausible and did not require the involvement of non-Iranian third parties to get to the point they're at now. Until any plausible evidence emerges that significant numbers of tweets were forgeries, I think the more reasonable position to take is to assume they're real and Iranian. Of course, this does not mean they should be automatically believed, as like all low-level eyewitness accounts they are necessarily subject to inaccurate rumours, flawed conclusions, personal biases and all the rest, but the mere fact that many of these tweets are inaccurate does not imply that they weren't posted in Iran and it does not diminish their value in letting the rest of us know what it's like for ordinary people at street level in Iran's cities.
How do we even know they are accurate? Twitter seems like a great propaganda tool.
Sorry after 8 years of Bush administration meddling in Iran (and decades of US meddling prior) why should we believe any of it. The people who died are just sad pawns in someone else's struggle.
My guess is that most are not, and that they are being written by people who are trying to sway public opinion.